Use an appliance thermometer for your refrigerator and, if possible, one in your freezer:
Put the thermometer in the middle of the refrigerator. After 5 to 8 hours, if the temperature is above 38° to 40°F (3° to 4°C), adjust the refrigerator temperature control to a lower setting. Check again after 5 to 8 hours.
Put the thermometer between frozen food packages in the freezer. After 5 to 8 hours, if the temperature is above 0° to 2°F (-18° to -17°C), adjust the freezer temperature control to a lower setting. Check again after 5 to 8 hours.