Can't change your App Store region because of a leftover Apple ID balance?

No. Apple never hands your balance to third-party apps. You type the amount in yourself - you can read it on your iPhone under Apple Account settings or in the App Store. Zero Balance asks for no login, no password, no verification code, and gets no access to your Apple ID.

It spends the leftover sitting on your Apple ID - the same balance that can keep you from switching App Store region. You enter the amount, the app lines up a few small App Store purchases to match it, and you see the total before you confirm.

Then an exact match may not be possible. Zero Balance shows you the closest option and how much it goes over - all before you pay - so you can decide whether to continue. Every purchase is confirmed separately through Apple's standard prompt.

The App Store doesn't let anyone charge an arbitrary amount - Apple only allows fixed prices for in-app purchases. So Zero Balance combines a few small items to get as close to your leftover as it can, with the least overshoot.

Yes, if it's the Apple ID balance that's blocking the change. Apple makes you spend the balance down to zero before switching country or region. If something else is in the way - an active subscription, an unfinished pre-order, a rental, or a pending refund - you'll need to clear that first.