The Quiltmaker Pro 18 is a rebadged HandiQuilter Avante. You might want to search on their videos for threading.
Loops on the back are almost always upper thread tension too low (if it was the bobbin tension, the loops would be eyelashes on the top). Be sure the upper thread is "snapped" into the tension discs. Also, if you are using a different thread on top, you will need to adjust tension from a previous thread's setting.