Medela Symphony question

Marianne
Hi! I'm new here :) LO was born in April and I went back to work last month. After using the Medela Symphony for 2 weeks now I need some advice....
#1 - I put a pic up - the part by my thumb....why is there a "screw on" piece that is outward facing? Is there an accessory that goes there or something?
#2 - when I'm double pumping and trying to hold both pieces on with my arm (to free up my hand) it leaves a big round impression mark on my forearm. Anyone else experience this and have advice on how to double pump without using that accessory band (I can't wear it at work)?
Thanks!