What version do you want to get? '''Note:''' Some versions of Quantum change how the data files are set up, so they are not backward compatible. Also, you can have both old and current Firefox on your system. Each must be installed in its own Programs Folder. When installing the older version, use the '''Manual''' option. Each Firefox version must use its own user profile. Lastly, the older version must be set up Not to update before use. Tell me what version you will be using for instructions. +++++++++++++++++++++++++++++++++++++++++++++++++++ [https://support.mozilla.org/en-US/kb/install-older-version-of-firefox?cache=no Install Older Version Of Firefox] {web link} Be sure to read everything here. If you still want to downgrade, look under; '''I still want to downgrade. ''' Click the '''Directory of other versions and languages''' link. Look for the directory of the version that you want. But, remember that '''old versions may have security issues. ''' You should also check out [https://www.mozilla.org/en-US/firefox/organizations/ Firefox; Extended Support Release] {web link} [https://www.mozilla.org/en-US/firefox/organizations/notes/ ESR Notes] [https://www.mozilla.org/en-US/firefox/organizations/system-requirements/ System Requirements]