Solved

KERS

Since the new update, both KERS cannot be used by both competitors at the same time
It would be good to remedy and restore it when it was still working.
I play on the phone - ios - this is the problem.

Thanks

Unfortunately on the mobile version of the app you can't use kers on both drivers simultaneously due to lack of screen space available, but you can use kers on both drivers if you use tablet or PC. 

How were you able to use it with both pilots at the same time? I have not ever known it being possible on a phone.

Ios Bluetooth keyboard would mean its possible to do it with a phone like you can on the tablet.... maybe...

I pushed the KERS button and changed the pilot. 

I confirm, it was possible earlier on the phone, as Gabor writes

Interesting...we've never intended for that to be possible, but I'm sorry to see it gone!

Hopefully in the future it'll be possible to use KERS for both drivers, in a cleaner fashion.