Unfortunately, I can't be of much help since I'm not sure what the "smth" button is or does and I don't even have a CLA yet.
That said, I'm not sure if you knew this already but you can actually access the CLA's owner's manual digitally from an Android
or iOS device
! Maybe it's just the geek in me but I think it's pretty neat!
You can also get it online at: http://moba.i.daimler.com/baix/cars/c117/cars/c117/en_GB/manual/index.html
I'm sure someone with actual hands on experience can help! Best of luck and enjoy your new CLA!!!