Hi,
By cursor I assume that you mean the playhead. The playhead is remaining fixed. But by changing the speed of the clip you are expanding or contracting the clip's display on the timeline, so the fixed playhead is at a different point in the clip. No way to change that.
What you can do is, before you change the speed, add a marker (Mark/Add Marker) to mark the position of the playhead. Then after the clip expands or contracts when you change speed you can move the playhead to the marker that you had set. That will put the playhead back at the same point in the clip that it was before you changed the speed.
-- Rich
-- Rich