Please don't touch your tension screw. Just a little to your left where the bobbin is sitting down in the case bring that bobbin thread back to your left while holding the bobbin down with your right hand, with the thread in your left hand bring it back close to the edge of the bobbin case make it go into a little metal groove and then possibly into another little slit farther left then bring it forward on the top so when you bring the thread up with the top thread it is caught in those little slits on the edge of the bobbin case which is your tension for the bobbin. It is your bobbin tension which is on the edge of the case. I hope you can see where I am talking about. will make 100% difference in your stitches.
Good Luck
Suzy