While there are more complicated fixes, this one is easy and inexpensive; and it might work for you. Suggest you try this before making any thermostat adjustments, etc., as the operation of your refrigerator may be OK as is.
Put a fan similar to the one below in the bottom of your refrigerator, with a clear air EXHAUST path upward to the cooling coils/fins. Do not block air INTAKE on fan.
Camco Fridge Airator - Walmart.com
Also, do not pack food tightly in the compartment; leave a little space between items to allow air to circulate freely.
Another item that makes it easier to check your refrigerator's internal temperature is an inexpensive indoor/outdoor thermometer, similar to the one below:
AcuRite Digital Wireless Thermometer - Walmart.com