By default, Windows 10 quietly reconfigures your default printer every time you print. This may not desirable, especially if you use different printers, or occasionally “print” files to PDF. “Let Windows manage my default printer” is new to Windows 10. When left on its default setting of On, Windows 10 will always configure the default printer to be the most recently-used printer.

1. Click Start.
   
2. Open Settings.
   
3. Go to the following page: Devices
   
4. See the option named "Let Windows manage my default printer". Turn it off as shown below: