How to format outline mode

I know how to format text documents, but I can’t figure out how to change the formatting in Outline Mode. It has changed all outline topics to the font I use for body text; not the one I use for document titles. I open Fonts, choose a new font and nothing changes. How do I set a default format for outlines?

The settings for Outliner appearance (and most other appearance settings for that matter) are in the Appearance preference pane.

To clear up one potential source of confusion, the Outliner has nothing to do with the contents of your file, such as how you choose to format it. Keep in mind the Outliner can also display lists of movies, or PDF files. It is a general organisation tool—you can think of it more like a Finder window or a Mail message list, than something like a Word outline—where in that case the outline is an extrapolation of the document, if that makes sense.