Originally Posted by quilticing
Have you adjusted the bobbin tension? It should feel like half as much resistance as the top tension. That usually works for me.
I don't know for sure but I wouldn't think the color of thread would make any difference but if I'm wrong someone with more knowledge about it will correct me.
As to brand, I have always used Gutermann thread up until yesterday when I started using Connecting Threads. Time will tell if it's ok. A quilting instructor once told me that Gutermann was the best and I never had any problems with it, but I've heard many other brands mentioned on here.