How to Scale a UI to Different Screen Resolutions?

FWIW

My UI resolution testing process is this:

  1. I open the game from the executable icon in the Windows folder.
  2. The game opens in the 1080p monitor by default.
  3. The UI works fine in 1080p.
  4. I use the command, r.setres 800x600w to resize.
  5. I move the resized game window to my 4K monitor.
  6. R.setres 3840x2160f
  7. The 4K UI is off-target.