How do I change my country for my Apple ID?

Use your iPhone, iPad, or iPod touch to change your region

1. Open the Settings app. 
2. Tap your name, then tap Media & Purchases.
3. Tap View Account. You might be asked to sign in.
4. Tap Country/Region.
5. Tap Change Country or Region.
6. Tap your new country or region, then review the Terms & Conditions.
7. Tap Agree in the upper-right corner, then tap Agree again to confirm.
8. Select a payment method and enter your new payment information and billing address, then tap Next. You must enter a valid payment method for your new country or region.* Learn more about how to change or remove your payment information. 

See this link for further reference

Change your Apple ID country or region - Apple Support