I am using ubuntu15.04. I have the superuser account and another user account. I can login either account with no problem. I clicked the gear button at the top right corner. I did see the two accounts listed, but when I clicked the other account, no response, no swtiching.
OK, I tried to lock the current account and thought I could then login the other. But in the locked screen, I can only see the current account listed, but not the other account, and so I cannot switch in this way either.
The only way I can switch user is to logout or restart the computer, and then login the other account.
Anyone can help?