I am a florist a mobile florist and this will be inside my shop. It is to hold fresh flowers. It needs to be between 36°F and 40°F so what temperature and what setting do I put it on since this is a Celsius setting, there is no 0 to 10 it is from -18 to -22 and then it displays 47 so what do I set it on? How do I get this to be the temperature that I need?