I recently applied several Windows 10 updates. After restarting my machine, every QT-based application I have on my machine has label text defaulted to 24pt font (which makes most of them unusable, or at least unwieldy). Where is this preference driven from, and how might I correct it?
A reboot resolved this issue. No idea what caused it, but the time-honored tradition of "just turn it off and back on again" did the trick.
I am able to reproduce this. It is caused when I set an external monitor on my laptop as my main screen. When I have the laptop screen as the main screen and the external monitor attached, it does not reproduce, neither does it reproduce with no external monitor. You have to reboot for the font change to take effect, i.e. between reconfiguring your display setup in Windows.
I posted the same answer here: https://www.virtualbox.org/ticket/16220. It seems to be the same issue.