Hello There were problem with skin file - Carbon. PSpad tels you that Carbon isn't available. When you select new dark skin, you got your "background" back. This isn't "screws up all settings", sorry. "screws up all settings" means PSPad destroys your PSPad.ini file and you lost all settings.
-- <https://forum.pspad.com/read.php?6,75339,75366> PSPad freeware editor https://www.pspad.com