So, I tried to follow everyone's advice! I tried feeling like there was a pencil between my shoulder blades, but it looks no different to before in terms of seeing my back muscles engage! I tried keeping my arms straight until I felt like I had my back/shoulders engaged, I tried not to flare out my elbowsand looking up to the bar. Does it look a y different to anyone else? My shoulder was still a bit pinchy at the bottom.