Is it set at the Default Printer?
If you haven't got Control Panel on your desktop or menu then the easiest way to find out is to click on the Small Win 10 Start logo, scroll up to Settings and click on that. Click on Devices which should give you a list of connected peripherals.
Make sure that your printer is listed then scroll down to the blue printed Devices and printers and click on that.
Control Panel will open (it sometimes takes a little while to populate first time) then scroll down to the printers and make sure that there is a green tick over your HP6940.
If not Right Click it and click on Set as Default Printer.