Updated (2/20/18)
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.
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. 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.
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.
Once you have installed the January 31^st^ update (KB4058258 (OS Build 16299.214)), you will be able to turn off this feature by going to Settings > Accounts > Sign-in options > Scroll down to Privacy > Toggle off Use my sign-in info to automatically finish setting up my device after an update or restart.
Note: The feature is not available on PCs that are managed by enterprises nor on home PCs that are sync’d to enterprise (work, school, etc.) email.