Mr Openoffice is happy with default A4 page

This is that kind of thing that you know you want to change, but there is always no time to do it. But it is just a minute, really!

http://selinap.com/2008/12/how-to-set-openoffice-default-page-format-to-a4/

Simply:
1) change page format
2) save it as a template (File -> template)
3) set this template as a default (File -> template -> organize -> commands -> set as a default tpl)

Do it, do it!