How Do I Adjust My Composition Length?

To extend your composition length in Autograph after creating a composition, start by clicking "Composition" and then "Show Composition Properties" in the timeline area on the bottom left of the default layout of Autograph:

This will then open the Composition properties panel on the right side of Autograph in the "Inspector" area:

You should be able to extend (or reduce) your composition there under the "Duration" fieldname!