Helped! wiki changed back to new look again-but wont let me change back!

I few weeks ago, my wiki got changed to a new look, I setted it back to the old look, but when I logged in today it was the new look again! I tried to do what I did last time, go to preferences and go to skins, select monaco - except there are no skins and monaco choices anymore!! How do I change back to the old look and also stop making it auto change into this new annoying look??