Shopify may be easy if you don’t need much custom stuff, but they make certain things unnecessarily difficult to do. one of those is changing the labels for the default contact form.
I tried to edit the theme’s code and eventually got the sections > contact.template.liquid but that showed a setting variable where I wanted to change text meaning that it was a setting that any Joe Schmoe might be able to set. But where is it?
I found it under the theme page > Actions > Edit languages.
There’s a tab for the Contact page: