To do a proper squat, lead with your hips to lower the body downward. You want your knees in same direction as your second and third toe. The goal is to get your thighs parallel to the floor.
To do a proper lunge, you want your back knee under your back hip as you lower downward. On your way back up, squeeze your glutes.
To get the most out of your back row, always bring your shoulder blades together at the top of the exercise. And remember to brace the core for more isolation.