i would suggest moving to the pulldown machine as a warmup, you need to work on actually feeling your lats it sounds like. Can you set up with pinched shoulder blades on the bench? For me, i like to retract my shoulder blades on most pulling movements to start and then pull back with the lower lats.
On a cable row with vbar, sit upright 90 degrees, lower those traps!, retract your shoulder blades and pull with the very middle of your back, and then hold it at your belly button for a second or two and just squeeze the shit out of your back, make sure ur traps are low! if u can feel ytourself shrugging up at all ur doing it wrong, you really need to learn how to relax ur traps and pull with the back.
yes i repeated that alot, but thats the idea, mid rep u may forget and go back to old habits, you need to become very conscious of ur movements.
For shoulders, id try hitting your rear delts first, then some side laterals, try leaning away ones where you hod onto something with one arm, lean away kinda making your body into a forty five degree angle, then doing laterals with one arm but dont try to go absurdly high, these really hammer the delts for me, try like 15-20 reps with a heavish dumbell.