Mh-z19b calibration

I recently bought the sensor and connected it to the esp. Seems like working, but shows strange values.

I guess it is because the sensor is not calibrated. But I have a question: will it keep calibration after power off?
I want to put it outside, trigger calibration and then put it back inside. Will it keep the base value?
Also it is not really clear if it will recalibrate itself every 24hrs. I don’t want that because in docs it says it will take the lowest value during previous 24hrs. What if my lowest value is 800ppm instead of 400ppm. It will show incorrect values after the recalibration.