The bottom crisper in my refrigerator is freezing everything....w

Look all the way to the rear of the control console in the fresh food compartment. Look up into the opening with a mirror. There should be a styrofoam diffuser (61005543) visible. If this is missing or damaged (many people think it packing material and remove it) it needs to be replaced. It spreads the air out rather than let it go right down the back wall to the crisper area.
One other thing to check is a tiny slot at the right rear of the same control console. a metered flow of air comes out the slot to the barrel shaped cylinder with the cold control capillary wrapped around it. Sometimes the slot gets water in it and freezes over. The unit will run too long and the cold air will settle during the off cycle and freeze items at the bottom. More often than not, when the slot freezes over, other items in the fresh food compartment will freeze......not just the bottom items.