When this account was created I was under the impression that my username is completely hidden from anyone. Is this the case and if not how do I change my username manually?
If you are referring/relating to what is displayed in the Forums ?
The terms/names are differ, first there is Your username, an email address (not displayed in the general forums) and Name (what is displayed in the forums to identify the poster), as you can see from the other contributors
It isn't actually the same and your email address is essentially hidden, to others, with exception to moderators.
Looks like you have been playing with your profile settings
See attached images.