When editing the default profile for Yakuake, I typed something into the Command box after /bin/bash. The result was that when opening Yakuake, it drops down and then slides back up while flashing. Keep trying this enough times and it will crash. The problem was also affecting Konsole. Konsole would exit immediately after launching it. I got Konsole working again by editing /.local/share/shell.profile and removing the garbage I had typed. However, this had no effect on Yakuake. I’m assuming there is a similar profile file I can edit somewhere for Yakuake, but I haven’t been able to find it.
How do I get things back to normal?