How to put down the back seat of Haifuxing in hippocampus?

On both sides of the back, near the place where things are put behind, the stereo bar, I don't know how to describe it, sitting in the back seat, with a short strap of schoolbag at the shoulder, one on each side. When pulled up, the seat will be put down as a whole, but if there is a seat cover for the car seat, it is not easy to install and it is very astringent, and the back seat can be directly connected to the trunk.