Australia: Has anyone been able to print to A4 size

Has anyone been able to change the default page size to A4? The standard seems to be American Letter, which looks slightly odd when printed on A4 paper. I submitted a ticket asking this question, and the David’s response was "Sorry but can you explain your printing needs? What type of printer and size paper?
regards,
David

Then when I didn’t respond within 24 hours (I had a day off) I got another response "I’m closing this ticket for now but feel free to reach back out to us if you have any additional questions. Have a great day! Regards, David

So much for support.

Anyone able to help?