i don't know why, i've always had thie problem. i play pretty fine while sitting down, but when standing up, even with the guitar quite high (a bit above belt line), i find really hard to to bendings on higher frets, or alternated picking and jumping strings. all my hands angles are really changing, the left hand reach the lower frets with a strange angle, and the picking hand, its just missing many time the strings while skeeping. its like you have to develop a different new skill to play standing? a different technique? any tips for how to get used to it?