No matter how I do them I feel my back and quads, not just my glutes. I try to get full range of motion, keep my head up, back straight. However, i feel my whole back, the upper part too, especially the part in contact with the bench. As I try to go lower and get full ROM my quads kick in too. What am I doing wrong? I try to start with high reps and just the bar then add weight. I feel it at lower weight too.