How do I use the temperature control?

Question

My EuroCave Comfort 260 wine celler has limited function control for the temperature setting.There are a U, a P and Up and Down electronic buttons. I have not been successful in setting a desired temperature. The included manual only has instructions for a more sophistiated temperature conctrol system with test buttons, which my cabinet does not have. What do the symbols stand for and how do I use them correctly?