I had an issue where one of my controls were missing altogether. I had to wipe my install file (which thankfully didn't kill savefiles) and install a newer version of Dolphin. I think somewhere there is a command to reset controls, but I could be mistaken. If the dropdown menu doesn't have it, then, you just have to reset it by unstalling and reinstalling.
Our android GUI leaves a lot to be desired...
Our android GUI leaves a lot to be desired...