Can't change country/region back to original.
Hello, in 2024 I changed my country/region for my apple account to Singapore and create a Billing Address that is also set to Singapore with random numbers on it to download some apps that aren't available in my country. At that time I thought it wasn't a big deal so I started switching to Vietnam and then Singapore again repeatedly until the change country/region option that was in the Account section in the app store disappeared. I thought that option will return after some time but its been a very very long time now and it still haven't came back. I didn't buy anything or purchase anything in this account and I also deleted all the apps that I downloaded in the country, but nothing worked. I did contact Apple and they told me that my account was underage in Singapore so I have to wait till I'm 16 to change it back, but at the time before this all happened, the country/region option was still there when I switched to Singapore. Now I am very desperate and doesn't know what to do, I really need to change back to my country. Perhaps I've done something bad so my account is now locked maybe?
iPhone 7 Plus, iOS 15