I can't switch to other machines in traffic mode

Good evening everyone, I want to ask how you can switch to other cars in traffic mode, I'm creating traffic, I want to change some cars, in the old version of the beamng drive game I could change without any problems, change some cars and ride on, and then I also click on tab and nothing happens, only if we create a separate other machine and can only switch to it and to my own. I would be grateful if someone could help.

 

Now there is an option whick you can turn on/off about this switch

 

in what sense?