I tried Samsung on line chat help yesterday but got nowhere so I thought I’d try here on the off chance that someone has the same model 
It’s a RF56J9040SR, side by side fridge at the top and side by side freezer underneath.
If I’ve understood the booklet correctly, I need the fridge at 37 and the freeze at minus 18 but when I try and change the freezer temperature it only takes me through from 5 to minus 5.
Help please
TIA