I've got those temperature controllers. They all look the same but can be very very different.
Yours displays the temperature within 0.1 deg C. However it will only let you set the temperature in whole degrees.
A long while back I got one or maybe two off ebay and they displayed and set the time in 0.1 deg increments.
They were OK and of course very cheap.
So a bit later I ordered about 4 more, I was aware of the ones that only displayed and set in whole degrees and avoided them by checking the photo's and descriptions only to find the ones I got were like yours, display in 0.1 increments set points only at whole numbers.
It is a very hard row you are trying to hoe here. You are trying to keep the eggs at 37.7 by using a different higher temperature. Obviously if you put the sensor at the eggs they will be at 38 so you are trying the sensor elsewhere.
It can appear like you can achieve this, for a while, but it is a furphy. When the temperature outside the incubator changes so too will all the variations in temperature of the incubator including the eggs. The only thing that will remain constant is the temperature around the sensor. Quite possible that the eggs that were at 37.7 at one time of the day go higher than 38 degrees at another time in the day.
IT ALWAYS MAKES MORE SENSE TO HAVE THE SENSOR AT THE EGGS BECAUSE THATS WHERE YOU WANT THE TEMPERATURE TO BE CONTROLLEDWhat you need to do first is calibrate your temperature controller. These things could be reading as much as a whole degree too high or worse still too low. So what you need to do is get your hands on an accurate thermometer. The only thermometers you will find that are reliable enough for this are medical thermometers. Those little electronic ones that you put in your mouth.
3/4 fill a largish container of water put the controllers sensor in there. Read the temperature on the controller and keep the water stirred as you adjust the water temp by adding cold or hot water. Not trying to control the waters temp, just read it using the controller.
What you want is the water temp such that your controller reads 38.0 and then see what the medical thermometer says. That will give you an indication of accuracy of the temperature controller. You can then use the settings on the controller to calibrate it so that it reads the same as the accurate medical thermometer. THIS IS AN ABSOLUTE MUST FOR ANY TEMPERATURE CONTROLLER YOU BUY!
Having done that you will now have an accurate temperature controller.
Now here comes the stinger for benen.
Benen doesn't want his temperature controller to be accurate
What Benen needs is for his temperature controller to read 38.0 when the water temperature is actually 37.7 as measured by the medical thermometer. Then he can put the sensor right at the eggs and away he goes.
So the end result is Benens will look at his incubator and see that it is set at 38.0 and regulating at what the readout says is 38.0 degrees. But Benen will know that if it reads 38.0 then the temperature is actually a perfect 37.7 at the eggs because that is where the sensor is.
So benen see how you go with this using the manual etc., any problems and I will dig out one of mine and give you really exact instructions. Don't panic if you find for some reason this doesn't work, for example if the calibration function only advances in whole degrees, I've still got a few more tricks up my sleeve.