Emilia Pretty much nailed it with her answer, but I thought I'd add that you'd use 'du' and 'dig' the same way you'd use 'I' and 'jer', except du/dig is similar while I/jer is plural. As a native English speaker, this was something I also struggled with for a while, haha. Someone please correct me if I'm wrong, but that is how I understand it, at least.