Have you tried the add-on All-In-One Sidebar? I really enjoy it and think it might fix your problem - https://addons.mozilla.org/en-us/firefox/addon/all-in-one-sidebar/

Are you using "Options > Bookmarks Toolbar" to display the toolbar? If you are, and it's not saving your settings when you close or restart Firefox, there might be a problem with your Firefox profile.

Try with a new profile and see what happens. Instructions here:

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

Thanks. Had merely been right-clicking and this did not save it. Much appreciated.

I have gone to Tools, scrolled down to Options and there is nothing called Bookmarks Toolbar there.

I do not want all my bookmarks displayed there. They are already among the menus at the top of the page where I want them. I only want the bookmarks I have selected as my Bookmarks Toolbar shown under the URL-field (where you enter the www.http...). When I open Firefox the Menu Bar and the Navigation Bar are shown. I have to go to the menu called View, scroll down to Toolbars, scroll down to Bookmarks Toolbar and click on it to get the Bookmarks Toolbar shown. To have do that every time I open Firefox is most unsatisfactory. Why is there no option to have the Bookmarks Toolbar shown without all that hassle every time whenever Firefox is open the same as is the case for the Menu Bar and Navigation Bar?

Yes, this is very helpful, and appreciated, but I think software should perform as it is (supposedly) programmed and not force the user to use a 'band aid' in order to solve his problem. But, again, thank you very much for the reply.