Enable sticky add to cart button on the customizer using legacy theme

By following these instructions, you will be able to change the scroll order on your customizer on your theme and have a sticky add to cart button just like this example. https://sign-product-customiser.myshopify.com/products/material-length-neon-customizer-demo

1. Open the Themes from your Shopify dashboard and click Customize to open the theme editor:
2. In the Theme Editor, click the top dropdown menu and find the template where your customizer is currently displaying:

3. On the left-hand side click on the " App Embeds" tab, it is the last icon on the list. Click on Neon Customiser Embed:

4. Ensure that Scroll Order is checked:

5. Test to see if this setting is compatible with your theme and hit Save.