I'm guessing you have a different Minecraft account registered other than this one, hence you have a new UUID. Think you'll have to register a new account or have it migrated to a new UUID. -V
MarcusX1999 was my old account I had SirWill transfer my donor rank to my new account Nuka_Break right after he did that is said username changed. And this is the username it gave me i'm just confused
Could you create a new forum account with the new minecraft account. Later on we can merge your two forum accounts.