Theme: Track, conductor path
   
   
    How can I move a signal segment? I always get a new corner / vertex instead...
   
   
   
If you want to move the element that you hit, you can drag&drop it directly, if you do not hit the small black box in the middle, but the track in between the 3 black boxes:
 (Image 1: Drag&drop by M1H here!)
(Image 1: Drag&drop by M1H here!)
Hitting a black box instead, will move or create a corner.