Visio 2007 - setting default page and font options

My question is simple, how do I change settings in Visio and have them stay
so every time I open the program, I don't have to set everything back up
again. For example, why does the program default to an A4 page size? Who uses
A4 sized pages??? I simply want to set it to "Letter" sized once and not have
to worry about it again. Also how do I set the global font size? I want my
font size for everything (text boxes, shapes, etc.) to be 12!!!!!!!! Why
won't you let me set this visio???

Thanks for your help