How to change my username?

Welcome to the forum ASL. In the mean time your username already got changed.

Yes, as tonymarshall said, simply send me a message if and I will take care of it for you. The use of the email address as usernames should rather be avoided, simply cause of privacy considerations.

In the upcoming site upgrade I will consider allowing a username change by the user themselves through a profile edit. Currently it doesn't update everything very well automatically.

Yes that is one of the issues that will never really be fixed automatically, even if everything else works properly. In those cases I'd have to manually run some update queries in the database, but mostly rely on people reporting outdated references or broken links. This is simply the nature of community websites which are always growing and changing. So if you come across stuff like that please click on the "Report to moderator" link of the post and I'll get it. It really helps.