Hey there..
U need to enable "Use two or three fingers for back/forward in pages" This way u can use the three fingured back/forward gesture in Finder, Chrome, Safari. The two fingered back/front pages is to switch between pages (which again is stupid, since u already have three fingered for that). It can be demonstrated in Safari. Open google. Search something random and click on any result and keep loading 4 to 5 pages. Then use three fingered gesture to normally go back and forth between pages. Now when u use two fingered back/front it does the same but with "different animation" So basically the two fingered pages is just a pepped up useless version of the existing three fingered gesture.
Also the bug which I found was that. The three fingered back/forth does not work in system preferences unless u do a two fingered back/forth gesture once.
Anyways really wish they add the Expose function of Snow leopard. Also the "show desktop" gesture of three fingers with the thumb is really annoying. The four fingered hide feature minus the thumb was so much useful. Everytime I need to use my thumb for this now. Please fix this apple or atleast give us the option to choose our own gestures.