How to change your default printer Mac OS.
Choose Apple menu > System Preferences, then click Printers & Scanners.
Click the Default Printer pop-up menu, then choose an option.
If you want the default printer to always be the same printer, choose that printer. The default printer doesn’t change even after you print to a different printer.
If you want the default printer to be the one you printed to last, choose Last Printer Used. OS X remembers the printer you used last at your current network location. For example, the printer you used last might change depending on whether you’re at home or at work.
Cr : https://support.apple.com/kb/PH18608?locale=en_US