shamelessly lifted from another post:
https://discussions.apple.com/thread/2700380?start=0&tstart=0
-----------< snip >-----------
To change the default Print orientation for Safari (and Preview, Mail, ...)
1) start TextEdit, or another Apple app that has a "page setup" dialog in the "File" menu
2) pull down the "File" menu, and open the "page setup" dialog box
3) change "Orientation" to the one you want as default, example: "portrait"
4) select "Save as default" in the above "Settings" pop-up menu
5) select "any printer" in the "Format For" pop-up menu (of course, if you want make the change for all your printers)
6) click OK and quit TextEdit
7) quit (if not done yet) and restart the other Apple apps (Safari, Preview ....)
The default orientation should have changed into the one you have selected and "saved as default" in the TextEdit dialog.
This has properly worked for me. Good luck.
-----------< end >-----------
and it worked for me!