Step 1: Log in to your account on medievalempires.com.
Step 2: In the account settings, you can edit/change the 'Player Name'.
Step 3: Don't forget to press 'Save' after you have edited the name.
Please note that a 4 digit, randomly generated number will be automatically added to the username that you choose.
FYI: 'Player Name' is the name displayed in the game, and will be viewable to other players.