Changing my students' usernames

It's impossible.

You can't change them as Ruta said. They told me they are going to work on this, because they changed the username of most of my students with the site update...

Hi everyone, want to clarify this situation. The reason usernames were changed in the new system is because the old system was not built properly and allowed duplicate usernames. This is a major issue for all platforms, and is best practice to not allow for security reasons. In order to solve this, we had to update these duplicate users with new usernames. Moving forward, the system will not allow duplicate usernames, however, we are looking at ways to allow you more flexibility to login or make it easier even if we can't edit or adjust the current usernames. Hopefully this helps explain what happened and why we needed to make a change.