Both stops, front and back are on the left rail, i.e. the rail next to the kitchen cabinet. You have to locate them by looking through the two rubber covers on the rail, using a finger to pull the rubber protection to the sides and allow you to peek through. Once located them, with a screw driver undo the screw just enough to be able to move the stop back or forward. You will need the screwdriver also to help you push the stop back or forward. Theoretically you could remove them altogether , I just left mine lying in there, inside the rail. The advantage, is by moving the seat all the way to the front I gain a huge additional cargo space on the back. On my last long trip I removed the portapotti from under the sink as I wanted the space just to be for groceries and kitchen stuff, into the boot right behind the bench. When , during the journey, my daughter (or me) needs the portapotti, I just slide the bench all the way forward, and I can just climb inside behind the bench into the boot, get the portapotti and do what I have to do. I can access the items in the boot very easily without opening the tail gate, and the cabinet next to the fridge.
When on site with some of the stuff unloaded from the boot, I slide the bench all the way to the back, or at least with the backrest well clear of the rolling door of the cabinet next to the fridge so that I can have comfortable access to it, and lots of space inside as in a living room.