Printer Page Size Settings

Last resort

I am no longer able to set my default page size (A4) settings in Word 2004 or Appleworks 6. US page size returns whatever I do when using an Apple Laserwriter 12/640PS printer. The A4 setting in the page setup dialogue is greyed out. When I select Any Printer the A4 option is available but it reverts back to US size the next time. How can I reinstate A4 as my default page size? I have used Printers and faxes system preferences but problem is not solved.
I am using a G4 mac with OSX 10.4. My Canon colour printer works fine. Can you help? My tech level is quite high.