I played around with my software on my machine last night and think I have solved the monogramming density problem. There was a tab I could go to that had choices of automatic or manual on the satin stitch. It was set to manual when I saw this tab. I thought that was strange. There was also a photograph of how the zig zaggety stitches looked in a little frame to the right. When I clicked from manual to automatic, the stitches in the photo were closer together so I thought, aha! I stitched out another B and it still looked the same. I went back to the tab and it was still on manual. I clicked automatic again and noticed a tool bar-like thing at the bottom where you had to click ok and I had not done that so I clicked it, stitched another B and it looked great, SO much denser and fuller and better - not white towel showing through! So I stitched another style B and another and another and they all looked good.
I still am going to take my little sample of all these B's back to the sewing shop and show them on their computer what I did and ask if they think that's the problem just to be sure. Technology and me are getting along a little bit better :)