Do you maybe need to change the foot to a rolled hem foot,and possibly the stitch length and width as well
kathi

My older Singer has a separate throat plate that must be used for rolled hemming, or you need a special foot. ( I use the plate). The stitch length is set for a close or fine stitch and the lower looper is set very tight. Also, rolled hemming with my machine is not suited for heavy or stiff fabrics. When I make napkins, I use wooly nylon serging thread which is recommended for a smooth finish.

If your fabric is not rolling, you may need a foot or another plate.

I've got everything set up according to the manual. Stitch length very close, lower looper very tight...I've tried fiddling with the tensions and even the cutting width. There is not supposed to be a special foot needed for the rolled hem. So frustrating! Thanks for the ideas.

My serger has a stitch "finger" that I slide back and out of the way, in order to make the rolled hem. Would your machine have that? Or is there a separate throat plate? Simply adjusting tensions and doing nothing else won't make the rolled hem, AFAIK. Do you have the owner's manual? It should have a picture of the necessary part and info.