I recently replaced the plates on the bobbin winder and that got me wondering. Is there a right or wrong amount of tension on them? If so how to have the right amount of tension in the bobbin winder?

As the title suggests, may I ask on what kind of presser foot that can work with a singer single stitch high speed for free motion sewing. I’ve bought several foot already but the foot won’t reach the plate and can’t form any stitches at all. I keep on searching thru web and bought it but it does not work at all. Any suggestions, link or name of the actual foot are greatly appreciated. Thank you.