App purchases requesting USA credit card info - I'm Canadian.

I've been trying to make some purchases on my phone (currently an in-app purchase) - but I can't!

Every time I go to make a purchase, the "please enter your credit card info" screen pops up. So I go along and start to enter all my info... name, CC number, ... and then it asks me for the state in which I live, and my zip code. This is where the issue lies... as I'm Canadian and nither live in a state, nor do I have a zip code (all provinces and postal codes up here!). Unfortunately, there is no spot on this screen to change the country that I (and my credit card) live in.

How do I change this so that I can make purchases? My phone seems to be convinced I live in Indiana 😕

Sidenote - I once heard of a hack to use Pandora (we don't have it up here) by entering a USA VPN in a Canadian phone. I tried it... it didn't work. The VPN is now deleted - but I'm pretty sure the state I chose at that time was Indiana.

It seems I've somehow screwed myself. Can anyone help with this?