One way I found to change it is to create a template with the font you want
to use set for the title.
Here's what I did:
created a new section with a blank page (for testing this)
change the font in the title area to 12 pt, Arial
clicked File | Page setup
saved the page as a template (on the bottom of the page setup pane) and
checked the box to apply this template for all new pages in that section.
Now when I open a new page in that section, the title defaults to 12 point
Arial.