To set a username for the first time:
1. Click the icon on the top right of the page:
2. Next to "No username" click "Create"
To change your username:
1. Click on your picture at the top right
2. Go to "Profile", and then click "Edit Profile".
3. You can change your username there by clicking the pencil next to your current username.
4. Note that you can only change your username ONCE
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Customer support service by UserEcho