Which Apple ID (email account) am I using?

More recent iOS devices (iOS 15, not sure which other versions)

1. Open the App Store app.
2. Look for an icon that looks like a person's head and shoulders in a circle. Tap that.
3. This should bring up the info regarding the account you're currently using.

An older version of iOS

1. Open the App Store app.
   
2. Click "Featured".
   
3. Scroll to the bottom of the Featured page.
   
4. The Apple ID you are currently using should be displayed here.
   

If you find that the game is using the "wrong" Apple ID, this page may help you to make the game use the correct account.