I heard about these bobbin boxes and found them at Amazon. I tried them and absolutely love them. The bobbins do not unravel at all and they fit snuggly in the foam and stay put. I have lots of them and label them according to what kind of thread is in each one. I replaced all of the bobbin boxes for all of my machines with these.
http://www.amazon.com/Set-2-Bobbin-B...s=bobbin+boxes