Since the mad rush for free upgrades a lot of users are struggling with the way Windows 10 handles default printers. By default there is a setting that is switched on that lets Windows take control of your default printer settings. Effectively this means that whichever printer you used last automatically changes to be your default printer.
This setting is not where you would historically change your default print settings and if you change it in the wrong place, as soon as you print again it changes the default printer.
The simplest way to turn off this feature is to click the Windows button in the bottom left of your screen and start to type the word printer, this should then adjust the start menu to show “Printers and Scanners”. At the bottom of this screen is a button which when clicked will turn the feature off.
You can then click the printer of choice and click on the set as default button.