How does a child account become a normal adult account? Is this something that happens automatically at a certain age? Or do I as head family account holder have to initiate something?

The reason I ask is because trying to use Edge on a child account is proving tiresome. Despite deleting my son's child account and re-creating it we are launching Edge and it is taking from anywhere between 10 seconds to a minute to become usable. When I say useable I mean the ability to surf, the actual browser is launched and you can go into settings etc BUT no web pages will load despite even typing web addresses in. It's as if Edge is waiting for MS server side to give it some kind of approval before it will allow any web activity. Once it's up and running it's fine but closing the browser session and relaunching Edge will bring back the long delay. Our adult accounts have no such issue using edge. Trying Mozilla Firefox on the child account also poses no such problems. We have no child restrictions setup online for the child account. So really he should be able to use Edge freely. But I feel the activity monitoring is somehow stifling the ability to use Edge.

If it doesn't improve I feel like abandoning the child account and just having him use an adult account instead. At least then Edge will start working quicker. But how does one convert child account to adult account. Or do we have to wait several years for his age to tick over?