many other people have been saying kinda the same thing, but you can improve your form by sweeping the weight up instead of shrugging it. If you can't keep your arms almost locked throughput the movement you may want to lower the weight.

those traps works cuz your form is not correct,you could go to youtube for it

it includes traps too maybe lower the weight so your trap dont take over durung the movement. This excercise works better light weight more reps