Mac OS X: 10.4 (Tiger), 10.5 (Leopard), 10.6 (Snow Leopard), 10.7 (Lion), 10.8 (Mountain Lion), 10.9 (Mavericks) 10.10 (Yosemite)
The default printer selected on your computer will always be the first printer selected when you open the print settings page. This can be changed to suit your printing requirements. For example, the printer that you use most often can be set as default printer to save you changing the printer selection for each print job. Follow the below instructions for your version of Mac OS X to change the default printer setting.
Click the Apple icon, from the top-left of the Desktop.
Click on System Preferences.
In System Preferences, click on Print & Fax.
Click on the Selected Printer in Print Dialog pull-down menu and select your printer.