I use monofilament a lot, and I have it in both the bobbin and the top spool. Before I switched to a special "metallics/monofilament" needle I had the same problem. As for the issue of getting caught around a baby's toe or finger, make sure to double-lock the beginning and end of each stitching session and make sure that your stitches are all the length that you have selected with no loooong stitches that can be raised up.