Long press the Library button in the navigation bar. This will bring up a list of your favorited libraries. There should be two buttons, toward the bottom: Reorder and See All Libraries.
To change your favorites, click See All Libraries. Once you done that, click Reorder to change the order those libraries’ hubs appear on the home screen.
You manage the hubs available for each library on the server, the same as always:
https://support.plex.tv/articles/manage-recommendations/
