By default, Firefox bookmarks show up in the order they were added. It is possible to arrange them alphabetically. Let me show you how.
We’ll start by opening Firefox and clicking on the Library icon at the top-right.
Click on Bookmarks.
Scroll all the way down the menu that opens and choose Show All Bookmarks. Or press Ctrl+Shift+B.
Choose the folder you want to search. I’m choosing the Bookmarks Toolbar. Hold the Ctrl key and right-click. Choose Sort by name from the drop-down menu.
The bookmarks should now display alphabetically.