High DPI screen support in Windows applications running on Windows 8/10 that use some other application framework than Microsoft's seems to be a real hit-or-miss proposition.
Qt, the framework that SE uses has this to say about it at
http://doc.qt.io/qt-5/highdpi.html:
In the longer term, the application should be adapted to run unmodified:
Always use the qreal versions of the QPainter drawing API.
Size windows and dialogs in relation to the screen size.
Replace hard-coded sizes in layouts and drawing code by values calculated from font metrics or screen size.
So maybe SE has some legacy issues in those points. There are bits of text in dialogs that are truly tiny on a UHD (4K) screen alongside correctly scaled text, and it's hard to determine what needs to be adjusted.
In the meantime, in the Fonts section of the Appearance options, increasing the font size of categories of text like "HTML Proportional" that are used in the SE UI seems to solve some problems (e.g. the text of the "About" dialog).
But scaling problems in Windows 8/10 seem never ending...
For instance, SE 22 and 23 both have really awful ergonomics with checkmarks in checkboxes, where the checkmark is not scaled correctly in relation to the size of the checkbox:
A quick Google search brought me to these Qt bug links:
https://bugreports.qt.io/browse/QTBUG-44478 (Windows 7 High DPI issue)
https://codereview.qt-project.org/#/c/164528/ (Proposed solution, abandoned)
https://codereview.qt-project.org/#/c/215633/ (A merge that apparently solved the issue, does SE use a version of Qt that includes it?))
I have zero knowledge about Qt, so don't take my instant detective work seriously...
