What security software do you have? Some security software uses a policy to inject their root certificate in Firefox to be able to intercept and monitor internet traffic and that adds a "Your browser is being managed by your organisation" message at the top of Options/Preferences. You can check the <b>about:policies#active</b> page to see whether policies are active (63+). *https://support.mozilla.org/en-US/kb/see-active-policies-firefox-enterprise You can inspect the Mozilla and Firefox keys with the Windows Registry Editor in HKEY_LOCAL_MACHINE and in HKEY_CURRENT_USER with the Windows Registry Editor to see whether GPO policy rules are active. *HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Mozilla\Firefox\ Note that the mere presence of the "Mozilla\Firefox\" key is sufficient to make Firefox display this notification, so if you have the Firefox key then remove it and only leave the Mozilla key or remove this key as well if it is empty. *HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Mozilla\Firefox\ =><br>HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Mozilla\

Thank you very much. I followed your advice and the problem is solved. Many Thanks.