In other words, his old MC account is linked to his current forum account. He cannot make a new forum account for his current MC account because his email is already being used, nor can he update his username because he technically has not had any name changes. Old MC account: The_Squid_Gamer Current MC account: The_SquidGamer Current forum account that cannot be changed: The_Squid_Gamer Forum account name that he wants, but can't because it's using his email: The_SquidGamer
I updated your account but it seems you have a second account with that name which will prevent you from using that name. If you can comment below with the other account and confirm the deletion of @The_SquidGamer account I can delete it.