My eldest, a former Windows user, has inherited an old iMac of mine which is currently running MacOS 10.6.8(?) Snow Leopard which, due to age, cannot take any later OS updates. He took it home before theCovid-19 lockdown and there is currently no way that I can travel to him to help out. He is not yet a comfortable Mac user as it is unfamiliar to him.
To the best of my understanding he has previously had an Apple ID which he used with a now deceased iPad, but he cannot remember the password and, on the Snow Leopard iMac he has been unable to get a password reset. I cannot understand why but I can't be sure exactly how he is trying to get it reset.
I suggested, therefore, that he create a brand new Apple ID with a new email address but he says that when he tries he gets an error message "To make changes to your payment information, you need to upgrade your Mac to the latest version of macOS."
I am at a loss as to how, at a distance, to advise him on where to go next.
Is it, perhaps, because the machine is still recognising that it is attached to my ID? has he not logged out of my ID? Is it a restriction caused by Snow Leopard? Could I create an Apple ID, using his email address, on my Catalina iMac then tell him the password I used thus allowing him to log in on his machine and change the password to one of his choice?
Or am I being a completely blind idiot and overlooking the bleeding obvious?
Any help or advice would be very much appreciated.