There was no such problem before - now I have the same settings for all cars, not like before for each of them. If I lower/lower the seat in car #1 and push it forward or backward, in car #2 there will be settings from car #1. Is there any way to do that for each of them there will be their own?
Have a look in your player.JSON for this line and set it to true like below. "User Vehicle Data":true, "User Vehicle Data#":"0=save with user mod data (in CCH files), 1=save separately (in all_vehicles.ini)", If you look in the all_vehicles.ini in the player folder you'll see it has settings for seat, mirrors and FFB steering multi in every car (by VEH file) you have installed.
Sadly what ADSTA mentioned does not work anymore. This bug started a very long time ago. Some cars save the seat settings and some do not. The cars that save the seat settings and those that do not change as well.