Looks like you need to close FreeCAD and open it up again to see the effect of any changes.
This was how I had changed it for undefined while seeing what was needed width 2 and dotted. Alibre default on the left for comparison

Went to change the appearance, applied and clicked OK. Added circles and they were the thin dotted ones. Closed FC and opened it up again, this time the circles was like this width 20 and solid
