there are many ways (eg, you can save layout first, and change layout to get buck default color, then load the sved layout ,,)
but if you hope not to tweak or save layout,,
１ change back gropund color from 3d view option menu
(R121 G141 B176) is default color.
and save the empty scene as default_bgcolor.duf,, (if you may need,,)
2 go to top menu, Edit preferences >Scene>Background colors
check on, ” ignore setting when opening a scene file.”
check on “Record settings when save the scene file” too.
it ignore the back ground setting when you load scenes, so you can keep the current back ground color.
when you want to get buck the recorded background color of each scene,
you need to check off ” ignore setting when opening a scene file” first,
then load the scene.
(you need not check off, “Record setting when save the scene file.” )
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