Changing countries and billing address keeps reverting

Have you added a credit card from the new country? Cancelled all your subscriptions?

If necessary, contact iTunes Support. Either use the form or scroll to the bottom of the page in the 2nd link. Follow through the screens to get a chat or telephone option.

iTunes Support

iTunes Support – world wide

You need to cancel all your subscriptions to change countries.

Purchases - View, change, or cancel your subscriptions

Purchases - Subscriptions not billed through Apple