I have my new-to-me QE 4.0 and I am trying to use two different color threads - one in the bobbin, one on top. I'm getting very slight show thru of the bobbin thread (it's the darker one, matching the back of a mug rug). I know it's the tension, but for the life of me, I cannot find where to adjust the tension on this new machine! Can someone help ASAP????