Hi!
I'll try it to explain, what Pioneer_Pixel means, but my english isn't perfect too ;-)
Driver 1 starts with following settings and the one he like to drive (Car FXR):
Front Camber -2.1°
Pressure 1.95 bar
wing 15°
rear camber -1.9°
pressure 2.00 bar
wing 7°
So, Driver 1 changes the car settings (F12 menu) to that one driver 2 like to drive:
front camber -1.5°
pressure 2.1 bar
wing 10°
rear camber -1.9°
pressure 1.90 bar
wing 7°
driver 1 enters pits, LfS changes the car settings (this settings are the right one which driver 2 like to drive). Driver 1 and 2 changes and driver 2 leaves the Pit. Now driver 2 enters Pit, LfS repairs car / changes tyres and so on - that's correct. At next Lfs changes car-settings again, without any interaction via F12 Menu from driver 2 bevor. So if you now look into F12 menu you can see a totaly changed set like:
front camber -2.0°
pressure 1.90 bar
wing 15°
rear camber -1.9°
pressure 1.95 bar
wing 7°
Now driver 2 changes the set back to the right settings he like to drive and do another pitstop, so LFS changes the settings back. From now on driver 2 can do so many pitstops he want - till the time, the next driver + car setting changes comes.