Changing the page orientation in Numbers 3.5.3
I had some issues with trying to change the print page orientation in Number 3.5.3
Here is the solution for anyone still struggling.
iMac (27-inch Late 2009)
select the menu item "File > Print...", then in the print set up, select the orientation (second section), then click "print" (bottom right) if you want to print, or "Done" (bottom right)if you want to continue working on your document: