When you first join the community, your username defaults to the first part of your email address. For example, my email address is [email protected] and therefore my username will default to @nicholas.
You may want to change your username from your default, especially if your email address doesn’t include your name in it. To do so, click on your avatar in the upper right corner of the screen and click on the gear icon in the drop-down menu to go to your profile preferences.
On the preferences page, click on the pencil icon next to your username to make changes:
This will take you to the username change page. Type your new username in the Username field and click the change button:
Usernames do have to be unique so if you’re trying to pick a username that is already in use you’ll get an error message. Pick another username that is unique and it will allow you to save.