aspect ratio changing for no reason

Beforehand set one image , preferably sticking to vertical/horizontal and not mixing them, to the original instead of what ever it's setting it for you, cmd+shft+C gives you the menu to select copy settings, select crop, go back to grid view and use cmd+a to select all your pictures and then just cmd+ V to paste the crop. This is the onyl way around I found but it still resizes it back sometimes, hope this helps you out.