Psoriasis Treatment on different parts of the body

Hello all, I used to have psoriasis really bad all over my body. Literally everywhere. Face, scalp, back, chest, arms and legs. I eventually got admitted to hospital with it and underwent tar treatment. I was in for around 2 weeks and the treatment worked everywhere apart from my arms. I've not had any more problems with the areas that it worked on but it just doesn't seem to want to shift from my arms. Because I hate the look of it and I feel that people would stare, I always keep my arms covered up. I've tried loads of different creams and gels on my arms but nothing seems to help. Has this happened to anyone else? I just find it strange that it's gone from other areas and just wants to stay on my arms. Any help and advice would be really appreciated. Thanks