How do you routinely adjust tension when changing threads?
I thread up my machine, thread the needle, and pull a couple of feet of thread through the entire path of the machine. I am checking for hitches in the thread path and I want tension on the loose side. Next, I single stitch to tie off, and then, at a slow speed, stitch a straight line. Many times I place a scrap of fabric in the margin of the backing beside the top for this. How does it look from the top? I feel the underside and run a fingernail along the stitch line. If there is a pop pop pop, the top tension is too loose. I tighten the top tension a little at a time until I see just a pin dot of the bobbin thread on the top side, then I back it off 1 or 2 clicks. If the piece is critical or I am doing points and curves, I will then do circles both clockwise and counterclockwise, inspect both sides, and fine tune for the best tension.