Hola! En este video explico como hacerlo:https://www.youtube.com/watch?v=88arY64oZbk

You can only edit that if you have Shopify plus, or a store previous to2019.

Unfortunately it is something you can only change if you have Shopify plus. If your store is previous to 2019, there is a way around because it allows you to add some code to the checkout (in theory for tracking)