You need to remove the rear seat in order to get to the rear panels.

My rear windows don't work all that well either, however I also put them down by gently pushing on them when I put them down, and gently pulling up on them when I roll them back up. In the summer I just leave all the windows down when I go places, I just figure I don't have anything in the car for people to take, and they can go ahead and steal the car if they like...