I follow your steps but the problem still unsolved.
1. in print preview, click the print button >> print dialog box bring up.
2. select the printer then click the properties button. >> There is layout
and paper/quality tabs.
3. in paper/quality tab, click Advance button. >> printer Advance option
dialog box bring up.
4. in printer Advance option dialog box. There is defualt paper sizes to
select. But can not define custom paper size.
Please kindly help.
Best Regards,
Boyd.