Magpi users initially log into Magpi with their email address.  If the email address is long, however, it is possible to select a username, which can be easier to enter during the login process (especially on a mobile device).

Do I Have a Magpi Username Already?

To find if you have a Magpi username, log into Magpi and look in the upper right corner of the screen for the phrase "You are logged in as ____".  

If the blank is an email address, it means you do not yet have a username.

If the blank is a word that is not an email address, that word is your Magpi username.

How Do I Create or Change my Username?

To create a username or change it, click on your email address or username at the top right of the screen ("testuserpro" in the image above).  That will bring you to your user pages, which have several tabs (Usage, Billing, User, etc).  Click on the User tab, and you will see a box where you can enter or edit a username.  Make sure to click the Save button when you are done.