I still can’t access the customised images even my account is 18 years old.

Hello, first it's a pleasure to be able to help you today.

My name is welcome to the community.

Hello OJacob1, unfortunately it is not possible to change a child account to an adult.

In your case, the ideal would be to add your account to an account of a family administrator so that he can give you permissions on the account so that you can make the changes you want.

Getting started with Microsoft Family Safety

https://support.microsoft.com/en-us/account-bil...

I got the same problem, even though I am not even in a family. My account is >18 years old and I
still get the parental control message that hinders me from accessing custom paint jobs and so on.

My Xbox account DoB is over 18 years old... yet many features of games I am not allowed to access. Strange...

In order to get the adult profile to work, I removed my 11-year old son's profile from the XBOX and then "connected" under my adult log in. Then, even after I reinstalled his profile, I could access my adult profile, but he could still not access it. My
18-year old installed his profile and my 11-year old can use his. If you really wanted to, I think you could create a false family member who is of the right age.

This is not an issue with Nintento Switch ...

I don't have access to the old account. That's the whole reason I was waiting the 5 years for it to expire, but 7 years later it's still not available to claim even though the old account clearly shows 7 years of inactivity.