Change of username, email address exposed

Somehow I only recently noticed my JIRA username is set to my email address. It should be the same as my minecraft display name, but I cannot change it myself. I can change my email, name and password fields, but not the username one.

Could you please set it to "Jack_McKalling", (exact case) without the quotes?

I'm not sure how it got there, but surely I never intended this. Linking to my user profile externally now literally shows my email address in the URL, but it is supposed to be private info. I could make a new account and discard this one, but I would rather not.

Thanks in advance.