How to change my iphone app store back to UK version?

I downloaded an app that could only be downloaded from the US store and so it automatically changed but now I can't figure out how to get it back to UK store.

Go to your settings on your phone and go to "itunes and app stores". At the top you should see "Apple ID: (your apple ID)". Tap it. A pop up should, well… Pop up with: "show apple ID" at the top. If you tap that, you need to type in your password.

When you did all of this correctly, you'll see a screen with some of your personal data. With also your country. Just change it to UK and you should be fine.