To sort your Firefox bookmarks alphabetically, you need to sort them folder by folder. Here's how:
- Click the menu button (three horizontal lines) in the top-right corner of Firefox.
- Click Bookmarks.
- Click Manage bookmarks at the bottom of the Bookmarks menu. This opens the Library window.
- In the Library window, navigate to the folder you wish to sort (e.g., Bookmarks Menu, Bookmarks Toolbar, or Unsorted Bookmarks).
- Right-click on the folder you wish to sort.
- Select Sort By Name.
This will alphabetically sort all the bookmarks within that specific folder. Repeat steps 4-6 for each folder you want to sort. Note that folders within a sorted folder will not be automatically sorted; you'll have to sort those individually as well.