Changing country or region without spending the remaining apple balance from gift card
You can’t use credit from your Apple ID’s previous country’s iTunes store in its new country. Because of this, you have to fully deplete the credit on your Apple ID before changing its country by purchasing stuff or giving it out as a gift to someone with an Apple ID with the same country. If the amount is too small to purchase anything or to give it out as a gift, you can contact Apple support.