If you are trying to change a student's username and you see the message shown below, then you have chosen a username that is already in use.

In Get More Math, the usernames must be unique for all GMM users.

You may want to add some numbers to the end of a name.

For example, if the username you are trying is joshbritton, and you see the error message, try adding numbers to the username such as joshbritton1234.