The freezer setting suggested by manufacturer works great, but the setting for refrigerator does not keep it at 40 degrees as recommended by FDA.  I put a thermometer in refrigerator and after increasing to highest setting of 5, it was at 44 degrees.  I moved the top shelf to near mid position to allow better airflow and now it is set to setting 4 and maintains a temperature between 36-40 degrees.  Happy with it now, but had to figure out how to make it work for me.