Both can lead to shoulder problems. If your eyes are positioned behind the bar it is likely that you will bring it too far down on your chest or hit the uprights as you press. Now pull your shoulder blades in and push your chest out. If you do not pull your shoulders in you again risk shoulder problems. So your upper body is planted firmly now it's time to set your lower body.
Buttocks stay firmly on the bench.
This is not what you want. Bring your feet as close to the bench as you can. We all have limited flexibility. Well your forearms should form a 90 degree angle with the floor at the bottom of the lift. As well they must be equally distant from the middle of the bar.