Changing country and payment method

Make sure you have no active subscriptions in the current

iTunes account

https://support.apple.com/en-us/HT202039

If you have a balance on your current account, purchase something

that costs more than the balance and pay the rest with credit card.

Or ask iTunes support to zero out your balance.

https://www.apple.com/support/itunes/

If you have cancelled all subscriptions, but some haven’t expired, contact iTunes Support. You need a valid credit card issued by a bank in the country the store is in, and you need a billing address in that country. If you have an account balance, either buy something more expensive and pay the balance with a credit card or contact iTunes Support and ask them to zero balance your account.

Purchases - View, change, or cancel your subscriptions.        

Purchases - Subscriptions not billed through Apple     

Region - Change your iTunes Store, iBooks Store, or App Store country or region.     

If necessary, contact iTunes Support. Follow through the screens to get a chat or telephone option.  

iTunes Support – world wide   

Apple Support schedule phone call