Hi number1poppy, when you right-click a folder and choose "Sort by Name", Firefox sorts the contents of that folder. To sort the "main level" of the Bookmarks menu, you can use either:

• Library window ("Show All Bookmarks" or Ctrl+Shift+b)
• Bookmarks Sidebar (Ctrl+b)

Right-click Bookmarks Menu and choose "Sort by Name" to sort that top level.

You may be wondering, "Can't I sort all of the folders in one step?" There is no built-in feature for that, but you could investigate whether an add-on could do it. One I saw in a search but which I have not tested myself is:

https://addons.mozilla.org/firefox/addon/sort-bookmarks-webext/

Please always read add-on reviews to learn about limitations and potential annoyances.

Note that Firefox sorts folder content between separators, so to sort a folder that has folders and bookmarks place all folders at the top and add a separator to separate folders and bookmarks.