@mintyfresh: I'm not a tailor but... Photos would help diagnose the problem and ask ProperCloth. I suspect armhole height has to be addressed at the pattern cutting stage. I doubt this problem can be resolved with alterations. Maybe this can be improved for your next shirt, but few MTM shirt companies can do high armholes so I doubt it. Having sufficient room across the back and some extra width and length in the sleeves improves mobility. Longer sleeves require properly narrow cuffs to prevent them from sliding down over your hands.