The #1 and #2 buttons are fairly straightforward and you can see the change easily. #3 lumbar adjustment is not quite intuitive and I found the below video helpful to explain how it works:
Unfortunately nothing much you can do about the rear. Would be helpful to know what version you had. Tesla did revise the rear seat cushions in the past, so might be possible to swap them. Otherwise maybe try one of those add-on seat cushions, but you would need to first determine specifically what is causing the discomfort (the bottom part, the seat back, the headrest, or somewhere else?).