Changing my Apple-Id's nationality
The App Store purchased items are tied to Apple ID per country.


If you have an Apple ID under registered under my.appleid@icloud.com in US, everything you’ve purchased is only available when you’ve switched to US App Store.
If you use the same Apple ID and switch country to Hong Kong, you won’t be able to download all the apps and musics you’ve purchased in US App Store unless you switch back to US App Store first.
You can, however, download the apps from the US App Store before switching to HK App Store where you can buy an apps from the there separately. The apps bought from HK App Store is only available when your Apple ID’s country has been set in Hong Kong.


For the sake of simplicity, never switch an Apple ID to other regions unless you decide to move to the destination country permanently.