In looking at the description in the source code, it's possible that setting browser.download.lastDir.savePerSite => false works going forward but doesn't clear directories for servers you downloaded from before. I don't know whether there is a way to clear out the database entries related to previous downloads without dumping some other data -- these are all stored together: * last upload directory per site * last download directly per site * last custom zoom level per site * last modified spellcheck language per site ''If you don't need that other stuff:'' Open your current Firefox settings (AKA Firefox profile) folder using either * "3-bar" menu button > "?" Help > Troubleshooting Information * (menu bar) Help > Troubleshooting Information * type or paste '''about:support''' in the address bar and press Enter In the first table on the page, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in File Explorer. Leaving that window open, switch back to Firefox and Exit, either: * "3-bar" menu button > Exit * (menu bar) File > Exit Pause while Firefox finishes its cleanup, then rename '''content-prefs.sqlite''' to something like content-prefsOLD.sqlite. Start Firefox back up again, and it should create a new empty database to start collecting data going forward. Any improvement with your download directory situation?