Hello hwfa, try to update from 3-bar menu > help (the question mark) and > About Firefox.

Do not try from the download site because the latest installers for Firefox on Windows Vista needs update KB2763674 (probably you do not have the update).

please see:

https://support.mozilla.org/en-US/kb/get-latest-version-firefox-windows-xp-vista

https://support.mozilla.org/en-US/kb/update-firefox-latest-version

thank you

The reason for WinXP and Vista users getting served 43.0.1 is because it is not possible to tell by the default browser useragents on whether the WinXP user has SP2 or SP3 and to tell if Vista user has patches like KB2763674 installed.

Firefox 43.0.2 and newer including 47.0.1 setups on Windows is signed due Microsoft requirements.

If you keep your Vista system updated then you can likely install the newer setups. Here is 32-bit Firefox 47.0.1 as you just pick language such as en-us. https://ftp.mozilla.org/pub/firefox/releases/47.0.1/win32/

Or you can do a update in Firefox 46.0.1 to 47.0.1.

Thank you ideato and James for your prompt replies. In the end it turned out that the problem was that I was not logged in as an Administrator of the system. As soon as I logged in as an Admin, Firefox updated to 47.0.1 without any further assistance from me. It seems that Firefox does not properly interact with User Account Control which allows a non-Admin to update software by quoting the Admin's password. Oh well, it is free software.

Hello hwfa, thanks for sharing with us

Well done, it is great you can solve the issue, please take a moment and mark YOUR reply/solution as "solution chosen" to help other with similar problem. :-)

(google basically show firefox chosen solutions when you search something in firefox forum)

thank you :-)

Done!