Time Machine turns off wrong monitor

Trece1, thank you for replying.

As I discovered the Display section within settings is copied if there is an existing user. I previously did make a minor change from the default settings when i first purchased this MacAir. That minor change appeared in the Display settings within the new user I created today.

I also already tried removing all login items as you described, no luck. Keep in mind this problem exists within Safe Mode where no login items or third party apps are loaded.

I also discovered that TM restore works just fine when I disable the 'Displays have separate Spaces' checkbox within the Mission Control setting. However that mode limitations when the external display is full screen.

Update...I ended up creating a new user with admin privileges and transferring all user files to the new user account. Warning, be aware that most instruction you will find regarding moving Mail accounts is outdated. There are a couple of folders and several plist files that you need to copy. See the apple_mikey post reply at Manual Mail Migration - Apple Community . Not all the plist files listed are used on my M1 but I copied what was found. I also suggest you do not copy the Keychain folder as many suggest. This caused me a world of password hurt to the point I had to start again. Backup Keychain to iCloud via the AppleID settings in System Preferences, your new account will access your Keychain from there. That is it...happy computing.

As my post indicated I have an M1 MacAir. NVRAM and PRAM reset do not apply. SMC reset only involves a restart (done). Re-installing the OS - done. All cables are new and rated for usb-c and HTML. All was well before the latest update (to Monterey 12.3). After update is when the issue came up. Keep in mind...backing up works fine. Going into Time Machine does happen, it is just that the wrong monitor is shut off. When entering time machine using dual monitors, the external monitor should shut off and the finder window is placed onto the laptop screen. But, in my case, the finder window is placed on the laptop screen then the laptop screen goes black and the external monitor remains on. Unplugging the ext monitor will turn the laptop screen on with the time machine finder window displayed. I have texted and spoken to apple support to no avail. They are at a loss.

Thank you, kamote0628, for your suggestion. I created a new user and behold...all worked well. Now comes the daunting task of determining what is wrong with my user setup. I already tried deleting my login apps. I also tried restarting into safe mode which is a very basic operating mode.

If you have any suggestions on how to proceed, I would be grateful.

Thanks.

alma1090, thank you for your input. There is no external monitor software involved. Problem also exists in safe mode which operates at a very minimal level...no third party anything.