It seems to me, whether it is Mojave, High Sierra or Sierra, after a power outage, my Mac re-boot automatically. After the re-boot, always some preference settings are changed, this especially noticeable for the displays. For example, I unchecked 'Use Stacks', after a re-boot the 'Use Stacks' is checked. In Mission Control, I checked 'Displays have separate Spaces' but after the re-boot, this check box mysteriously gone unchecked. Do other people have this issue? I have a late 2012 Mac Mini with Mojave 1.4.