If you want to reset the route of the line from where you happen to have deviated to vs. your prior "line", you have to set "reset'.
It works that way on both the Furuno 3D, Nobeltec, and Northstar systems that I have available. From the helm, I have both the Northstar and Furuno systems; and from the Nav Station, I have the Nobetec, plus the other two available. I usually do NOT steer from the Nobeltec, which is on our PC below.
I think that's pretty typical for these systems.