Hello Dennis,
you must set the heating characteristic correctly. It takes some time to find the optimal setting of the heating characteristic. Normally you should have found the ideal setting after one heating season. The best way to do this is as follows.
Set the room thermostats in all rooms where you always want to be warm (kitchen, bathroom, living room, ...) to the highest possible level. Set the other rooms, such as the bedroom, to the desired lower temperature. Then you have to set the room setpoint temperature on the control to the temperature you want for the living area. Now you only need to make changes to the characteristic curve according to the temperatures in the rooms to be heated. Because you have turned up the room thermostats to full, you will notice the necessary changes immediately. Please change the inclination and the level according to the tips under the following link.
Translated with www.DeepL.com/Translator (free version)
https://www.viessmann-community.com/t5/Innovations-Blog/Das-Viessmann-Heiztechniklexikon-H-wie-Heizk...
Best regards
Flo
