People squat differently.
Some swing when they are rising up. Full squats have worked on my hips, quads, hams, but have roughed up the patela on my knees... So they are different for each person
The feet are a problem, I only squat with flat shoes, Adiddas shoes for olympic weightlifting are the best, and even Converse shoes, because they are flat at the bottom, giving you a better stance. I got so used at using the flat shoes, that when I forget them, I drive back home to get them.
this is a pic of the shoes
ecx.images-amazon.com/images/I/41Z%2BpTE1b%2BL.jpg