I have a Winforms Application (C#, .NET 4.7) that has no problems on my system with a 1920x1080 monitor. I have set the AutoScaleMode to Font for my main window, and added the true to my manifest. Running the program on a computer with a High resolution (3840x2160) screen seems to work fine as well. All is scaled correct and everything is readable. Until I open a datafile and display the results on the Map or Chart control. Then the whole program suddenly rescales to about 50% of it's original size and all fonts become unreadable small. Changing the font size or resolution using the Windows display settings has no effect. What could cause this runtime scaling, and how can I work around this ?