Go chiro or physio. They will check and teach you some exercise based on your condition. Keep doing those exercise. Chiro and physio is not magic, those session will not make your posture automatically good. You still to do some exercises and maintain it

Need to check what the cause of your bad posture. Maybe those exercise from youtube not helping as it target different muscle. Sometimes, your muscle too tight causing bad posture, just need to release it. Other time, over develop and under develop muscle