It takes 2 clicks to get back to a full screen program

My roommates messed with my settings and I have been able to set most things back but theres one thing I cant figure out. It only takes one click to open a program, say safari. It opens automaticly in full screen mode, but when I am back at my desktop and want to return to safari just by clicking it on my dock, it takes two clicks when it used to take one. Ive looked all over but i cant find it anywhere!