There is probably a problem with the file that stores the preferences, for details on fixing that see https://support.mozilla.com/kb/Preferences+are+not+saved

Thanks, I read the article yesterday, and it was of no use. The file is not locked or read only, and as I said it my original question this is a brand new installation of Firefox, and a newly reformatted hard drive, so the issue of a corrupted file is moot.

With Firefox closed try renaming prefs.js to prefs.old then see if you can save the settings. If Firefox can then create a new version and save the settings it will indicate a problem with the current file.

Also did that yesterday, made no difference. That is why I resorted to posting here, none of the so-called fixes posted here or elsewhere on the Web have been of any use.

Which settings are not kept?

Does Firefox save changes in prefs.js ?

Did you check for the presence of a file user.js ?

content,max.tokenizing.time; content.notify.interval; content.switch.threshold; nglayout.initialpaint.delay; network.http.max-connections; network.http,max-connections-per-server; and network.http.persistent.max-connections-per-server are the ones I have been trying to adjust, however, I tried other settings as well, just to see if some were saved. No matter which setting I try to adjust, the changes are reset the moment I restart Firefox. Prior to restarting, the changes I make are listed as Modified Preferences in the Troubleshooting Information, but as I said, they reset the first time Firefox is restarted. There was no user.js file, so I created one. Still made no difference.

Are you using cleanup software like CCleaner ?

I use ATF Cleaner, however, there is no automatic mode, and I do not do any manual cleaning in between making the changes and restarting Firefox, so this is not an issue with a cleaner affecting the files. I simply make the changes, the changes are there, restart Firefox, the changes are gone. Absolutely nothing in between. I have done two complete, clean re-installs of Firefox (three if you count the brief time I suffered temporary insanity and installed Firefox 4.01),

It seems that I have solved the problem. By allowing javascript to access the clipboard, the changes I made are now being saved and implemented correctly. Thank you both for your help.