I'm using the latest High Sierra on my macbook air with an external acer monitor. I recently did a clean install, and noticed that display mirroring gets reset after every shutdown. Before my clean install (I had the same High Sierra before) when I reboot, my monitors would be mirrored automatically, since I had set it that way. However now, whenever I reboot, I have to manually turn on mirroring every single time I reboot. Why is the setting not sticking? The only user account I have is an administrator.
update: strangely, I toggled the settings, shutdown, and now it is sticking. I'm not sure what caused it.