click on "instant 3d" function and then select the sketch and pull the arrow in any direction
the ruler snaps automatically.
you can change the position of the sketch by just using the coordinate axis that become visible on clicking on any surface.
but first solidworks will ask should the relations to be kept or not.
if the sketch is fully defined then the no option will work.
if you are using a sketch that is drawn on a extrude feature then if we pull inside the body the cut feature will be used
and if the sketch is not fully defined then every face properties can be changed