I need to change the address on the JotForm I am using in my Shopify shop

Are you referring to the URL of the form?

You have an option to use a custom URL. Please refer to this guide: How-to-Create-a-Custom-URL-of-a-Form. Here's an example: (https://www.jotform.com/username/formtitle).

You may also use custom domains here in JotForm. Please check this guide for more details: How-to-use-Custom-Domains-with-Jotform.

Hope that helps. If you have any questions, let us know. Thank you.