When you modify Windows 10 resolution from 4K to FullHD, Dopus is resized at the same time.
When you resolution babk to 4k from FullHD, Dopus will remain in the FullHD size.
Are you rebooting after changing DPI settings? You need to in some cases. (Not just for Opus but for parts of the OS. In fact, some things take two reboots for some reason; e.g. standard status bar heights.)
Oh, okay that's good to know, the switch between resolutions is problematic in quite many cases, just wondered if Dopus had solution for it, but if it's OS based thingy, then there's not much to do. Thanks for the quick reply & help Leo! 