How to change my Apple ID to another country?

The support article Change your Apple ID country or region - Apple Support describes how to change your country setting on everything using your Apple ID, and the requirements and results of doing this.

Follow the steps in the support document you posed from. It explains exactly what you need to do to change your country. Change your Apple ID country or region - Apple Support

Are you having an issue with those steps?

If so, explain what that is.