Refrigerator not getting cold enough

How do I get my refrigerator between 2 and 8 degrees Fahrenheit?

I need to keep my vaccines at a temperature low enough to stay useful which is between 2 and 8 degrees but I don't know how to do this. I bought a new Danby refrigeraotr and it keeps going below 2 degrees. It actually went to -1.8 degrees which will ruin any live vaccines.

I have the setting at the maximum coolness and the temperature keeps on dropping below the temperature range I need. What do I do?