1) Open the Terminal application
2) Type in the command: cupsctl WebInterface=Yes
3) In a browser, go to the webpage 127.0.0.1:631/printers.
4) Select the printer you’re wanting to change, using the link in blue.
5) Under Administrator, proceed to select the “Set default options”.
6) This will open the options so you can see what options you can change and set them to what you’d like.
7) When you’ve completed this, click the “Set Default Options” at the bottom of the options list.
8) It’ll prompt you for your username and password. Enter this in and press the “OK” option
This is completed at this point!
However, if you wish to disable the Web interface, go back to the terminal and enter this command: cupsctl WebInterface=No
I hope this helped you with changing your default printer settings on Mac OS X.