Preferencias de usuario vs. predeterminado para la página de inicio

This question is similar to the closed topic User preference for default home page, but it’s still not clear to me. I originally set the default home page to Categories, by placing it first in the list. If I now (two months later) change the default to Latest, what will happen? I can see two possibilities:

  1. Everyone who has not explicitly set their User Preferences currently has a null, or empty setting, so they will see the new default setting of Latest.

  2. Everyone’s User Preferences were filled with Categories- the default at signup time- so they will still see Categories. Changing the default now will only affect new users in the future.

Which one is it?

Until we get a better answer, I can only tell that I think everyone who did not change their settings or whose settings were same as site default, will see their settings changes to new site default (your option 1.).

Because I never touched my settings and used to see Latest but when site default went from Latest to Categories, my personal settings were set to Categories, I had to manually go back to Latest.