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How to Customize a Shopify Theme Without Losing Future Updates

Anurag Pandey
Last updated on November 14, 2026
Shopify, Shopify Plus
19 minutes read

Two Shopify stores on our client list run the same Shopify theme. One installs every new version within days of its release, checks the preview and publishes it without a second thought. The other has refused to touch updates ever since its last attempt quietly erased the product tabs, the size chart and the trust badges that customers relied on before buying.

When the owner of the second Shopify store first reached out to us, he was convinced the Shopify theme itself was faulty. It wasn’t. Both Shopify stores are heavily customized, both worked with capable Shopify developers, and both run Shopify apps for reviews and upsells. The only real difference is where those customizations were made. In the first Shopify store, almost every change sits in places Shopify carries forward. In the second, the changes were written straight into files that every new version replaces.

That is the part most Shopify store owners are never told. Done the right way, Shopify theme customization never has to stand in the way of Shopify theme updates, and you don’t have to choose between a Shopify store that looks exactly how you want and a Shopify store that stays current.

In this blog, I’ll explain what really happens during an update, what survives and what doesn’t, and the exact rules and steps my team follows to keep customized Shopify themes easy to update.

How Shopify theme updates work

Every Shopify theme in the Shopify Theme Store is built and maintained by a Shopify theme developer. Dawn is made by Shopify itself, while Shopify themes like Prestige, Impulse and Symmetry come from independent design studios.

These Shopify developers keep releasing new versions of their themes to fix bugs, improve page speed, add fresh sections and support new features from releases like the Shopify Winter ’26 Edition.

When a new version is ready, Shopify shows a notification in your Shopify theme library under Online Store > Themes. You can open it, read the release notes and decide when to install it. Each Shopify theme also displays its current version number, so you always know how far behind you are.

What happens next depends on one thing: whether anyone has touched the Shopify theme code.

If the code has never been edited, Shopify can usually update the Shopify theme in place, and your Shopify store simply moves to the new version.
If the code has been edited, Shopify adds the new version to your Shopify theme library as a separate, unpublished Shopify theme. Your live Shopify store stays exactly as it is until you publish the new version yourself.

The two layers of every Shopify theme

To understand Shopify theme updates properly, picture your Shopify theme as two layers sitting on top of each other.

The first layer is your settings and content. Every time you change a color, pick a font, add a section or type a heading inside the Shopify theme editor, Shopify saves that choice in configuration files. The main ones are settings_data.json and the JSON files inside the templates folder.

The second layer is the code. These are the Liquid, CSS and JavaScript files that decide how the Shopify store looks and behaves. You see them when you open the Shopify theme code editor through Online Store > Themes > Edit code. Here is what each folder in that editor holds:

Folder	What it holds	Usually changed through
layout	theme.liquid, the master frame that wraps every page	Code editor
templates	JSON files that list which sections appear on each page type	Theme editor
sections	Liquid files for each section, such as the header, footer or featured collection	Code editor
snippets	Small reusable pieces of Liquid, such as a price label or a product card	Code editor
assets	CSS, JavaScript, icons and fonts	Code editor
config	settings_schema.json (which options exist) and settings_data.json (which options you picked)	Both
locales	Text for buttons and labels in each language	Both

Shopify protects the first layer during an update. The second layer gets replaced with the Shopify developer’s new files. That single fact explains every lost customization I have ever been asked to recover.

What gets kept and what gets lost during an update?

Anything you set through the theme editor travels with you to the new version. Anything typed directly into Shopify theme files does not.

A skincare brand once came to us after an update wiped out the ingredient tabs on every product page. A freelancer had built those tabs by editing the main product section file. Nothing was wrong with the tabs themselves. They simply lived in a file that the update replaced, so they vanished the moment the new version went live.

Here is a clear picture of what survives and what doesn’t:

Change	Where Shopify stores it	After the update
Colors, fonts, logo and spacing chosen in Shopify theme settings	Settings files	Kept
Sections and blocks added, removed or rearranged in the Shopify theme editor	Template JSON files	Kept
Text, images and links typed into sections	Template JSON files	Kept
Code added in the Custom CSS box of the Shopify theme editor	Settings files	Kept
Code pasted into a Custom Liquid section or block	Template JSON files	Kept
App blocks and app embeds switched on in the Shopify theme editor	Settings files	Kept
Edits made inside existing Liquid, CSS or JavaScript files	Theme code	Lost
New section or snippet files you created	Theme code	Not copied, must be moved by hand
Code an app pasted into your Shopify theme files	Theme code	Lost
Products, collections, orders, customers, pages and blog posts	Shopify admin, outside the Shopify theme	Never affected

New files you created are still code, so Shopify won’t copy them into the new version on its own. The good news is that because they sit in their own files, moving them takes minutes instead of days.

Your Shopify store data is never at risk. A Shopify theme only controls how your Shopify store looks. Your products, orders and customers live in the Shopify admin, and no Shopify theme update can touch them.

Why skipping Shopify theme updates isn’t the answer

After losing customizations once, many Shopify store owners decide never to update again. It feels safe, but an old Shopify theme slowly costs you speed, features and support.

The problem is that an old Shopify theme stands still while everything around it keeps moving. Shopify keeps adding features, Shopify apps keep changing how they connect to Shopify themes, and the Shopify theme developer keeps fixing issues your Shopify store may already be facing.

Here is what you give up when you stay on an old version:

Speed improvements. Speed improvements. Shopify theme developers regularly trim heavy code and improve how images and scripts load, which helps your Core Web Vitals scores. Faster pages mean better conversions.
Bug fixes. Issues with variant pickers, filters or the cart drawer often get fixed in newer versions.
New platform features. When Shopify adds something new to themes, Shopify developers bring it in through updates. Older versions never receive it.
Shopify app compatibility. Newer Shopify apps are built for the modern theme structure. Older versions can create conflicts.
Shopify Developer support. Most theme support teams will ask you to move to the latest version before they look into a problem.
A harder jump later. Every skipped release adds to the gap. Moving across one version is easy. Moving across six is a project.

So the goal is not to avoid Shopify theme updates. The goal is to customize in a way that makes them painless.

How to customize your Shopify theme safely?

To customize your Shopify theme safely, keep as many changes as possible in the settings layer, and keep the rest of your code small, separate and recorded. These are the six rules my team follows on every Shopify theme customization project.

Always work on a duplicate Shopify theme first

Before you change anything, go to Online Store > Themes, open the actions menu next to your live Shopify theme and click Duplicate. Make your changes on the copy, preview them, and publish only when everything looks right.

This gives you two protections at once. Your customers never see a half finished change, and you always have a working backup sitting in the Shopify theme library.

Code is unforgiving on a live Shopify store. A single missing bracket can hide the Add to Cart button or break the product page, and every visitor sees the problem until someone fixes it. On a duplicate, the same mistake shows up only in your preview, where it costs nothing.

Use the Shopify theme editor and Shopify theme settings

Modern Shopify themes (often called Online Store 2.0 themes) put a lot of power inside the Shopify theme editor. Before asking anyone to write code, check whether the editor can already do what you need. Everything done here survives updates automatically.

A few changes people often pay Shopify developers for, which the editor can handle on its own:

Moving reviews above the product description: drag the blocks into a new order inside the product section.
A different layout for one product: create a new product template in the Shopify theme editor, then assign it to that product from the product page in your admin.
Extra details like care instructions or ingredients: Shopify store them in product metafields and connect them to a text block using a dynamic source.
Small styling tweaks: add a few lines to the Custom CSS box in Shopify theme settings or in a single section.

Use app blocks instead of code injections

Older Shopify apps used to ask you to paste their code into your product template or theme.liquid, and some injected it automatically. That code disappears on the next update. Worse, it often stays behind as dead code after you uninstall the Shopify app.

Modern Shopify apps use Shopify theme app extensions instead. These come in two forms:

App blocks that you place inside a section, just like any other block.
App embeds for floating widgets and background scripts, switched on from the App embeds area of Shopify theme settings.

Both are stored as settings, so they carry over to new Shopify theme versions. Before installing a Shopify app, ask its support team one simple question: does your Shopify app use app blocks, or does it edit my Shopify theme files?

Add custom code in separate files

Some features genuinely need code. That is fine. What matters is where the code lives. Shopify liquid customization becomes update-friendly when your work sits in its own files instead of being mixed into the Shopify developer’s files.

Liquid is the template language Shopify themes are written in. It pulls Shopify store data like product titles and prices into your pages. You can write it in three places that keep updates simple.

Custom sections and snippets

Shopify custom sections are new section files you create yourself. In the Shopify theme code editor, open the sections folder, click Add a new section and give it a clear name such as custom_size_chart. Add a schema to the file, and the section appears in the Shopify theme editor like any other, ready to be placed on any page.

Snippets work the same way for smaller pieces. You build the snippet in its own file, then call it from the Shopify theme with one short line:

{% render ‘trust_badges’ %}

That one line is the only change inside the Shopify developer’s file. Everything else is yours and easy to move.

Separate CSS and JavaScript files

Instead of adding your styles to the Shopify theme’s main stylesheet, create a file such as custom.css in the assets folder and link it once in theme.liquid. All your style changes then live in one place. For only a handful of lines, the Custom CSS box in Shopify theme settings is even better, since it survives updates without any copying.

Custom Liquid blocks

Most modern Shopify themes include a Custom Liquid section and block in the Shopify theme editor. You can paste small pieces of Liquid or HTML into it, such as a delivery estimate message or an embedded form. Because the code is saved as a setting, it moves to new versions automatically.

What about a Shopify child theme?

If you have used WordPress, you may be looking for a child theme. In WordPress, a child theme sits on top of a parent theme and holds only your changes, so the parent can update freely underneath it.

Shopify has no official Shopify child theme system. A theme cannot inherit from another theme. The approach above is the closest you can get: settings in the editor, custom code in its own files, and only tiny, recorded edits inside the Shopify developer’s files.

Document every code change you make

Keep a simple change log for your Shopify theme. A spreadsheet is enough. When an update arrives, this log becomes your checklist.

Date	File	What changed	Why
12 Aug	sections/custom_size_chart.liquid	New file	Size chart for apparel products
12 Aug	layout/theme.liquid	Added one line linking custom.css	Load custom styles
20 Aug	Product card snippet	Added discount percentage label	Show savings on collection pages

It also helps to mark your edits inside the code itself with Liquid comment tags, like this:

{% comment %} ControlF5 custom: discount label {% endcomment %}

Now anyone opening the file can find your changes in seconds.

Use version control for heavily customized Shopify themes

For Shopify stores with a lot of custom code, a spreadsheet is not enough. This is where version control helps.

Shopify lets you connect a Shopify theme to a GitHub repository straight from the Shopify theme library. Every change is then saved with a record of what changed and when. Shopify developers can also use Shopify CLI to download the Shopify theme to their computer, work on it and push it back.

The real benefit shows up during an update. Your Shopify developer can compare your customized version with the Shopify developer’s new version file by file and see exactly which lines need to be reapplied. Nothing gets missed.

How to update your customized Shopify theme step by step?

If you have followed the rules above, an update becomes a calm, predictable job. This is the exact process we use at ControlF5.

Step 1: Read the Shopify theme’s release notes

Open the update notification in your Shopify theme library and click to view the release notes. They tell you what the Shopify developer changed, fixed or added. Compare that list with your change log. If the Shopify developer rewrote a section you also edited, expect a little more work on that file.

Step 2: Add the new version as an unpublished Shopify theme

Click Add to Shopify theme library. Shopify installs the new version as a separate, unpublished Shopify theme and copies your Shopify theme editor settings into it. Your live Shopify store is not touched. For a Shopify theme bought outside the Shopify Theme Store, download the new version from the Shopify developer and upload it as a new Shopify theme.

Step 3: Move your custom code to the new version

Open the old Shopify theme and the new Shopify theme in the Shopify theme code editor, each in its own browser tab. Then work through your change log line by line:

Recreate your Shopify custom sections and snippets in the new Shopify theme as new files, and paste in their code.
Upload your custom CSS and JavaScript files to the assets folder.
Reapply the small edits inside the Shopify developer’s files, such as render lines or the link to custom.css.
Switch on any app embeds that need checking, and confirm each app block still appears where it should.

One rule matters more than all the others here. Never paste a whole old file over the new one. That throws away every fix the Shopify developer just shipped in that file. Add only your own lines.

Step 4: Test on desktop and mobile

Preview the new Shopify theme and click through the Shopify store the way a customer would. At a minimum, check:

Home page, collection pages and filters
Product pages, including variant selection, size charts and any custom tabs
Add to Cart, the cart drawer and the cart page
Search results and the customer account pages
Every Shopify app widget: reviews, upsells, wishlists and popups
The same pages on a real phone, not just a resized browser window

Step 5: Publish and keep the old version as a backup

Publish the new Shopify theme during a quiet period, never in the middle of a big sale. Keep the old version in your Shopify theme library for a few weeks. If something unexpected shows up, you can publish your old Shopify theme again in one click while you fix the issue. Your Shopify theme library holds up to 20 themes, so there is room for a backup.

Mistakes that cause problems during Shopify theme updates

Most difficult updates I have seen trace back to a handful of habits. None of them looks harmful at the time, which is exactly why they keep happening.

Picking a Shopify theme that needs heavy code from day one. If your must have features (mega menu, product tabs, color swatches) are missing from the Shopify theme, every one of them becomes custom code you will carry forever. Choosing a Shopify theme that already includes them saves you work at every future update.
Treating every request as a coding job. Many Shopify store owners hire a Shopify developer for changes the Shopify theme editor could handle in minutes. Each unnecessary code edit is one more thing to move later.
Assuming an uninstalled Shopify app is gone. Uninstalling a Shopify app does not always remove the code it added to your Shopify theme. Those leftover lines can lead to a slow Shopify store or throw errors. Clean them out before an update so you don’t carry them into the new version by mistake.
Letting several people edit with no shared record. Shopify store owner tweaks a file, a freelancer adds a feature, a Shopify app injects a script, and nobody writes anything down. When the update arrives, no one knows what was changed or why.
Treating a duplicate Shopify theme like a Shopify child theme. A duplicate is a full copy of the theme, not a layer sitting on top of it. Code you edit inside the duplicate is still a code edit, and it faces the same problem during the next update.

When to bring in a Shopify developer

If your changes are limited to Shopify theme settings, Shopify app blocks and a couple of Custom Liquid blocks, you can handle updates on your own. Some situations, though, are better left to someone who works inside Shopify theme code every day:

Your Shopify store has custom features spread across many Shopify theme files, such as bundles, product configurators or custom checkout messaging on the cart.
Your Shopify theme is several major versions behind, and the Shopify developer has rewritten the sections you customized.
Nobody kept a record of past changes, so the custom code first has to be found before it can be moved.
The Shopify store drives serious revenue, and even a few hours of a broken product page would cost real money.

A Shopify expert will not just copy code across. They will move your existing work into custom sections and snippets, replace old injected Shopify app code with app blocks, and leave you with a Shopify theme that is far easier to update next time.

At ControlF5, one of the best Shopify agencies, Shopify theme customization is one of the many Shopify services we offer. We find custom code hidden across Shopify theme files, rebuild it as clean Shopify custom sections, and bring outdated Shopify themes up to their latest version with every feature still in place.

You end up with a Shopify store that looks the way you want and updates without stress. So if you need help with Shopify liquid customization, if you want to customize your Shopify theme safely or update a heavily edited Shopify theme without losing a thing, talk to my team here.

Final thoughts

Shopify theme customization only becomes a problem when changes are hidden inside files the Shopify theme developer owns. Once you know that Shopify protects your settings and replaces your code, every decision gets simpler. Use the editor first, keep custom code in its own files, write down what you change, and test every new version before it goes live.

Do that, and Shopify theme updates stop being something you fear. They become a routine task that keeps your Shopify store fast, current and ready for whatever Shopify releases next.

Frequently asked questions (FAQs)

Question: Does updating a Shopify theme delete my content and settings?
Answer: No. Everything you set through the Shopify theme editor, including colors, fonts, sections, text and images, is copied into the new version. Your products, orders and customers are not part of the Shopify theme at all, so they are never affected. Only direct edits to theme code are left behind.

Question: Can I customize a free Shopify theme and still update it?
Answer: Yes. Free themes like Dawn and the Shopify Horizon themes receive updates just like paid ones, and the same rules apply. If you customize your Shopify theme safely through the editor, app blocks and separate custom files, a free Shopify theme updates as smoothly as a premium one.

Question: What happens to app code when I update my Shopify theme?
Answer: Shopify apps that use app blocks or app embeds carry over, because they are stored as theme settings. Shopify apps that pasted code directly into your Shopify theme files lose that code. For those, reinstall the Shopify app or ask its support team to set it up again on the new version.

Question: How often should I update my Shopify theme?
Answer: Read the release notes each time an update appears. Small bug fix releases are usually quick to install. For bigger releases, plan a time when the Shopify store is quiet. Checking for updates once every quarter keeps the gap between versions small and manageable.

Question: Can I undo a Shopify theme update if something goes wrong?
Answer: Yes. When you add an update to your Shopify theme library, the old version stays there untouched. If the new version causes a problem after publishing, simply publish the old one again while you fix the issue.

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Anurag Pandey

I lead ControlF5, a Top Rated Plus agency specializing in WordPress, Shopify, and GoHighLevel development. With over 4,000+ successful projects on Upwork, 150+ verified reviews on Clutch, and 300+ completed projects on Freelancer, my team and I help global brands grow through strategic design, automation, and SEO excellence. Holding a B.E. in Computer Science, I’m passionate about combining AI-driven workflows and GoHighLevel automations to simplify marketing, boost organic SEO, and scale customer engagement. I actively share insights across web development and AI communities to help others navigate the evolving digital landscape. For me, web design isn’t just about aesthetics, it’s about building SEO-optimized, conversion-ready experiences that create measurable business growth in the AI-powered era.