Threading Orange Overedge Stitch Needle - Singer Quantumlock 14T957DC Detailed Threading Manual

Slip the thread into the third slot on the right next to the take-up lever, then into
the third slot on the right in the guides just above the needle clamp. Next slip
the thread behind the metal guide and then into the eye of the needle in B
position, and then under what looks like a bridge at the back of the foot. Pull
the thread tail to the back of the serger.

Threading Orange Overedge Stitch Needle:

Top Cover Thread Guide
Thread the top cover thread guide by slipping the thread under the guide from
right to left, and then pull the thread under the small round disk from the right
side.