If you have added a lot of personas to Firefox, and some of them are no longer available in the Add-ons window, it is because Firefox only keeps your 8 most recently used personas.

If you have more than 8 personas, you can either bookmark each personas page or keep track of them with a free personas account.

Bookmark each persona

Bookmarks let you save links to websites you've visited. If you want to use a persona that is no longer in the Add-ons window, bookmark the persona, and visit that page when you want to use it.

1. Go to the home page of a persona.
2. Click on the star icon in the Location bar. The star icon will fill in and your bookmark will be created in the Unsorted Bookmarks folder.
3. Repeat steps 1 and 2 for each persona you want to bookmark.

Keep favorites in a personas account

With a free personas account, you can keep a list of more than 8 favorite personas.

1. Install the Personas Plus add-on.
2. Create a Personas account.
3. Manually add any favorite personas to your favorites.
4. You can access favorite personas by clicking on the personas icon in your status bar and selecting My Favorites from the menu.