Hi

You will need to update to a more recent version of Windows first. This may require a new computer.

Firefox 116 and newer require Windows 10 as the minimum, users on Windows 7 and 8 and 8.1 have been moved to Firefox 115 ESR.

• https://support.mozilla.org/en-US/kb/firefox-users-windows-7-8-and-81-moving-extended-support
• https://download-installer.cdn.mozilla.net/pub/firefox/releases/115.33.0esr/

Beside updating your Windows to Windows 10 or 11 the only other way to use a more current version of Firefox from Mozilla like 148.0.2 or 140.8.0esr is to say dual boot with a current Linux distro.

However if the CPU on your system is 32-bit then the 32-bit Linux options are much more limited and Firefox 145.0 and later dropped 32-bit Linux support.