i recently bought an adapter and so i have been trying to set up a PS2 controller for steam big picture mode but I'm not sure how to save the settings (steam doesn't make it very obvious) and the PS2 doesn't have the same buttons as other controllers so I have had to miss a few out. Has anyone else had the same problem?
Well, you can use a 360 controller emulator like x360ce. It essentially turns your PS2 controller (or any controller/interface device) into a xbox 360 controller. You assign what buttons on the dualshock 2 correspond to which buttons on the 360 controller. And since most controller based games/software are set up for the 360 controller, it should cover your bases.
As a side note, I used to do the same thing you are. At first I struggled to get motioninjoy to work with my six axis controller (PS3), and eventually got tired of the pain in the ass, and got a usb adapter for a dualshock 2 since I much prefer the design of the playstation controllers. And it worked for the most part (it was wiggy with some games though, like the Arkham games), once you got used to what button does what in each game... but so many games are set up for the 360 controller that heat of the moment button promts/quick time events can be an issue (it tells you to hit X, which on the PS2 controller is the bottom button, when on the 360 controller it's the left button etc). I just wanted something that would work and I didn't have to think about, so I decided to just say screw it and grabbed a 360 controller. Haven't had a controller based issue since.
I do still prefer the playstation controller layout, but the xbox layout is fine. Though I do wish more games would be set up for multiple controller types, not just the 360 controller. It would make things a lot easier for those of us with different preferences.