So here's my problem that I would like to get improved:
1) I select a setup for a car and I don't modify it at all
2) I decide to select another car
3) I change my mind again and decide to use that car which I was initially going to use
4) Now I notice my problem: the setup which has been selected is that car's default setup.

So here's a thing I would like to get: game could remember the last setup you've selected for all cars, even after you have changed your car. So if I want to use the car that I was initially going to use, the setup that I selected last time before changing a car should be selected automatically.

Yeah, it remembers setups in clicking order, if you decide to sort them by date. But it only counts setups that I have modified after I have selected them. If I just simply select a setup without modifying it at all and then decide to use another car or just decide to leave the pits, it doesn't get placed into front of that "date-list".

In my opinion, this is small, but still very annoying problem at the moment.

+1 to this.

But what you could do is, for example, give simple but easy to remember names and add symbols so they appear on the top of the list.
For example:
I have a XRG setup called BL1_race but I have to scroll for a while to get to the setup, so instead I rename it to 'BL1_race, or [BL1_race] , so the ' / [ ] character/s will make it appear on top of the list, and so on with the important setups. At least that's what I came up to avoid scrolling 5 minutes to find a setup xdd.

yeah this would be nice (maybe an option in game settings?)
burned myself in a league race on this, checked fuel for someone in other allowed car and didn't notice it switched to default after going back to my car...

took a couple of trips to gravel to figure out what's happening

so deffo +1 from me

very good suggestion and should be easy to implement