From the photo, it looks like you're measuring the temperature of the fridge. Opinions vary slightly as to the optimum fridge temperature but mostly somewhere between 2C and 4.5C although temperature often varies a little throughout the fridge cabinet - especially with glass shelving (as you appear to have) and no air circulating fan (which your fridge may or may not have).
Your thermometer seems to be reading about 6 or 7C but as foxhole has said, leaving the fridge door open for more than a few seconds will cause fridge temperature to rise. If you want to get an accurate temperature measurement, place the thermometer half-way back on the middle shelf, close the door and leave for a couple of hours (assuming the fridge is already cold and nothing warm has recently been put in it). Then open the door and immediately take a temperature reading (don't take longer than a few seconds). If the reading is still above 5C then either lower the temperature some more and repeat this process (you say the fridge is set to the lowest setting but it looks like the control could be set a little lower?). If, even on its coolest setting, the temperature is still above 5C then something is wrong with the fridge or it's being used in an unsuitable environment (i.e. environment too hot or too cold).