Sometimes when you try and print to a network printer which is not your default printer and has the kind of paper size you want to (for example 11 X 17 or Tabloid), you try and change the page setup in Word and you cant seem to have the right paper size available in page properties even though you have choosen the right printer.

This is because the printer you are trying to print to is not the default. If you temporarily make this printer your default, the paper size would become available and everything would be fine.