Dynamic Scaleable User Interface
In the included image one can easily see the large discrepancy between the font size on the desktop and Substance Painter. The screen resolution is set to 3840 x 2160 and the desktop has been zoomed by 25%. It appears to me that either the underlying UI components are a bit dated or just do not consider the higher display resolutions that are available today. Even though I am using a 43" monitor I need to be no more than 12" away to be able to read anything. I should add that I am in my 60's so that has some bearing.
Please take the time to look into manual/dynamic resizing of the UI fonts and Icons.