Lady Diana

Don't touch your tension, until you check your needle and thread. Your needle has to match your thread weight.
What size needle are you using. Most use a 90/14 topstitch needle with the large eye. Do you have loops, or what we call eyelashes from turning corners and making circular design too fast. If your hand are moving faster than the speed of your machine, then you will get those. Check your thread path....all clear....no hang ups? Superior Threads has information on their site for thread weight and needle match up.....but do check to see that you are using the 90/14 topstitch needle before messing with your tension.