How can I change my posting name or "screen name" to something else?
Changing your username is not an option, unfortunately, so you'll have to register a new ID. You will lose your posting history (though the posts themselves will remain under the old ID), favorites, etc, and start from scratch if you register a new username.
Only one username can be registered per email address, so if you want to switch usernames, you will either have to use a different email address, or, if you don't have one, let us know at firstname.lastname@example.org, and we can work some magic on the back end to free up this address for you.
If you decide to go with registering with a different email, please let us know when you're done so we can deactivate this account, as having two active accounts isn't permitted.