Thanks Greg. I think you misunderstood (or I poorly described) my question. I'm able to separately set resolution and scale for each monitor through Display settings. That works fine, and most of the time I have things set to the native resolutions of each screen which, because the laptop is "UHD" 3840 x 2160 and the monitor is plain old 1920 x 1080, are different from each other.
What I'm trying to do is easily go back and forth between different combinations of a changed resolution and scale on either or both screens with 'presets.' Most importantly, I want to have one set of laptop/external monitor resolutions/scales using those native resolutions of each and another set in which, say, the laptop's resolution and scale is changed to a non-recommended resolution and scale setting. And at times, I may need a third different combination.
(It's a little difficult to explain why, but optimizing the CAD screen as I described above is the primary reason. I doesn't display correctly on the laptop's native res. Most other programs can figure it out so that when I drag a window from one screen to the other, the window adjusts to display correctly on the other screen once the window is fully within that screen; this CAD program doesn't do that.)
I can certainly make these changes manually. [Though when I reduce the laptop's resolution to "fake" it being 1920 x 1080 (at 100% scale) even though its native res is 3840 x 2160 (which looks good at 225% scale), the display settings become tiny and I can barely read them until I "keep" the new settings, but never mind that minor problem.] What I'd like to figure out is whether I can easily switch between pairs of settings with a preset rather than having to manually go into scale and resolution each time. It'd be cool if the preset button were on the taskbar, maybe in the notification area. Or something easy to get to like that.
Think of it as like the presets on a fancy lighting control in a room where you might have one button to push for, say, setting all the room lights for "watching tv" and another for "entertaining'" or "reading" in which the lights are at different brightnesses. You only have to select one preset, not individually adjust each light.
Does that description make sense?