Fortunately you can easily change it. If you go to https://appleid.apple.com and login using their account details, in the Password and Security section, you can change the year of their birth. 1/1/2001 works fine, I think the key is that they need to be over 13 to change from Adult to Child account.
Benjy Fenwick (d. 1981) was a wizard and member of the original Order of the Phoenix. He fought in the First Wizarding War and was murdered and mutilated by Death Eaters before the war's end.
Filius Flitwick is the Charms Master at Hogwarts and the head of Ravenclaw, and is described as being a very short, dwarf-like person. He is also mentioned as having been a model student and a former duelling champion.