Re-synching is only necassary if your car has one touch "up" one touch "down" windows, to re-synch, operate the window to its lowest position and hold switch fully down for approx 3-5 seconds, then repeat procedure for the fully up position, repeat on all 4 windows.
Well to be honest I did,nt know it had to be as I have never consciencely turned the key too pos. 2, to synch the windows, but as I normally forget too re-synch them after battery reconnection, and left to do them as i,m reversing off the driveway, I suppose mine has always been in pos. 2.