In the Vintage “Trademark” theme, the H1 is likely hardcoded in the Liquid files, which is why you don’t see a setting to change it in the theme customizer.
Here’s how you can update it:
Edit the Theme Code
Go to Online Store → Themes → Actions → Edit code.
Check files like index.liquid, product-template.liquid, or collection-template.liquid.
Look for <h1> tags and update the text inside, or replace it with a Shopify variable like {{ page.title }} for dynamic content.
Check Theme Settings
Sometimes H1 text can be edited via Customize → Sections → Homepage or Banner settings. Look for any “Heading” or “Title” fields.
Use Metafields (Optional)
Create a metafield for H1 text and update the Liquid file to pull from it. This allows future edits without touching code.
Tip: Always backup your theme before editing Liquid files.
The <h1> tags in collection-template.liquidonly affect collection page titles. They do not change product page titles.
For product pages, check product-template.liquid (or similar files) for where {{ product.title }} is rendered. You can wrap that in an <h1> if needed, but make sure each page only has one H1 for SEO purposes.
So editing the collection-template will only impact collection titles, not the product titles.
That’s been my struggle, haha. In product-template.liquid, the is no {{ product.title }} in the file. Currently, the product.title is H1, but we want it to be H2 and change a different element to H1 for SEO.
Below is the current code in product-template.liquid. Is it possible to add something in to change the product title from H1 to H2? I can see from the html on the website that it IS pulling from product-template, but I’m unsure how to edit it.
For some specific themes on Shopify, the H1 tag on product title is set with hard code indeed, like what @Nobble said here. Therefore you cannot change it directly from customization page and need to change by finding related product liquid file.
I can help you locate the related codes on the website. Please proceed to share your store URL so that I can continually work on it to express more clearly. Thank you!