Change Display Settings before Login in Ubuntu 22.04

  1. Use Settings app to configure the display settings after login and save.
  2. Copy your user’s monitors.xml file into the home folder for gdm user to make it take effect before login.
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sudo cp ~/.config/monitors.xml ~gdm/.config/monitors.xml
sudo chown gdm:gdm ~gdm/.config/monitors.xml

References

Is there to make the login screen appear on the external display in 18.04?