See Change, add, or remove Apple ID payment methods https://support.apple.com/en-us/HT201266
Here are the rules for changing your country. See the support options for getting help with your problem.
Change your Apple ID country or region https://support.apple.com/en-us/HT201389See this heading especially What to do before you change your country or region.
Use this link in the document if you need to View your Apple ID balance https://support.apple.com/en-us/HT202359
If you can't complete any of the steps, can't change your country or region, or you have less store credit than the cost of a single item, contact Apple Support.
And you also can contact iTunes worldwide support via text or chat using this link https://support.apple.com/choose-country-region/itunes