If you have any separators in your bookmarks list, the sort stops at the first separator. You need to sort at the top of every separator for the bookmarks between each separator, assuming you are sorting in the Sidebar.

I didn't know about separators -I don't think i saw any -(I asked ask .com what they were) so I can't get rid of them-thanks for your help any way-by now you know I do very little on the computer-I keep on saying i will take a class but I haven't -so I have very limited knowledge but i will keep on trying Thanks anyway

Sorry that I didn't explain separators for you, I guess that is an undocumented feature in Firefox these days.

Separators are horizontal lines in the Bookmarks Menu, in both the Sidebar and the Bookmarks drop-down from the toolbar view, of Bookmarks. Firefox has 5 separators in the Bookmarks drop-down from the toolbar menu (which can't be moved or deleted), and none by default in the Bookmarks Sidebar.

If you right-click in with the Bookmarks Sidebar or the Menu drop-down, there is an item labeled New Separator to add a separator to separate bookmarks and/or folders. The new separator can be used as a visual line boundary for grouping bookmarks and folders, or be used to 'mark' the start and end of a group for sorting purposes. That way the user can alphabetically sort a related group of bookmarks and folders (folders will be sorted to the top alphabetically, followed by the 'loose' bookmarks sorted alphabetically), while other bookmarks and folders above or below a separator won't be sorted at all. Or each group between the separators can be sorted, for multiple groupings of bookmarks and folders - each with its' own sort