The WidgetReflector settings are not saved. The widget reflector is a developer tool; it isn’t meant as a proper DPI scaling setting. Rather, it is a way for you to play around with various scaling settings and ensure that any widgets you are authoring work correctly.
The editor does not currently respect the OS’s DPI setting. There IS a mechanism that scales game content based on resolution. You can read more about it here: DPI Scaling | Unreal Engine Documentation
Meanwhile, all the underpinnings for respecting the OS’s DPI scale are there. You should be able to hack it real quick by calling FSlateApplication::Get().SetApplicationScale(2.0f)
.
EDIT: One caveat is that the editor has not been extensively tested with non-1 DPI scales. You may find some bugs specific to the editor app. If you do, we’d love for you to report them so that we can get on fixing them.