I have multiple posture problems

Great question, and you are not alone in dealing with more than one thing at a time. Most posture issues are connected, so fixing one often helps the others too. I would suggest starting with whichever problem bothers you most or feels most limiting, build some consistency there, then layer in the next focus. The app is set up to help you work through programs progressively so you are not trying to fix everything at once and burning out.