We’ve heard the feedback that some of you would like to have a switch for turning on and off this feature, and have now added the ability to do this. This is to create a seamless experience wherein, if you have to reboot your PC, you can pick back up from where you left off and resume being productive.
What changed? The advanced Windows Update feature which restores running applications after an update has been extended to regular shutdowns and restarts initiated through power options available on the Start Menu and various other locations. There is a change with the Fall Creator’s Update where applications that have registered via RegisterApplicationRestart will re-open after a shutdown or reboot. This has far-ranging impacts across the OS (in a good way). The desire is to create a seamless experience wherein, if you have to reboot a PC, you can pick back up quickly from where you left off and resume being productive.
If you want to start with no apps open (other than those set to auto-start via Task Manager/Start), you’ll need to ensure all apps are closed before shutting down or restarting the PC. This is actually a change in the core functionality of Windows in this development cycle.