Peak Pilates Reformers and understanding gears

I am looking for someone to please explain the Peak gear and footbar system to me. I have never ever used them before and visited a studio that had these. I had to move my footbar to second knotch and then it felt odd so the teacher mentioned trying to change gears using a stopper...?? I was taken aback because the teacher didn't seem to understand her own machine. As I may well be teaching there I am looking for a kind soul to explain the Peak system to me. Please pretty Please .Thanks