Tools/Preferences, save prefs. Includes object defaults (what you set by hitting TAB last time you placed one).
What, you haven't backed up your prefs before? Yikes, what if Altium mega-crashes and you need to "factory reset" it?
I also highly recommend saving your 2D and 3D layer view configurations (if you aren't using the defaults there as well), and your GUI layout prefs (positions of panels, command shortcuts -- yes, you can change some of these! -- that sort of thing).
Keeping these handy shifts your recovery time from several hours to tens of minutes.

Speaking of recovery, don't forget to enable auto-save, and you can move where it stores backups -- I moved mine from AppData to a common-projects subfolder, easy to reach. Just as well, you can keep a link to it handy.
Tim