I'm using my brothers google account so i download an app he bought, but even though i'm on the account and synced it and everything, it still says i need to buy it. idk what's wrong, could location be the problem? he's abroad sorry if this is a dumb question ._.
If you have multiple Google Accounts on your device, you have to change the active account in the Play Store to the second, third, etc, one and make it active.
Open the Play Store app, tap the 3 line menu, and you should see the active account on the left and the "unselected" account on the right, tap the icon on the right and go to the app, you should not be able to install it.