Hello and welcome.
Did the machine work on your last project? What were you working on?
Did you follow the number sequence for threading?
You want to be sure the pressure foot is raised before threading.
Go to the tension setting and re-set to the default setting. It will be hi-lighted in black.
Have you been in FMQ mode? Turn the hand-wheel towards you to re-set the machine.
Do you have the bobbin the case correctly? Let the thread hang down in a "p" shape and insert in to case.
I have the Crescendo and have never changed tension setting for stitching. Love the laser light and the walking foot. There are different feet for it; SITD, Open toe, and one with the 1/4 guide which is great for stitching on binding.