Windows 10 1511–Default Printer
With the 1511 update to Windows 10, a change was made how the default printer is automatically configured. The last printer used will become the default selection. To disable this feature, access Settings –> Devices –> Printers and scanners. Turn off the “Let Windows manage my default printer” option.
The Registry Key for this parameter can be found at:
HKEY_Current_User\Software\Microsoft\Windows NT\CurrentVersion\Windows\LegacyDefaultPrinterMode
Set the Data value to "1" to return to the old behavior.