Hi, you can update Firefox using the instructions here: [[Update Firefox to the latest release]]

Since you appear to be using the old EOL Windows 7 the most current version of Firefox you can run is Firefox 115 ESR currently at 115.32.0esr and the last update will be 115.33.0esr on Feb 24. https://support.mozilla.org/en-US/kb/firefox-users-windows-7-8-and-81-moving-extended-support You can download Firefox 115.32.0esr at https://www.firefox.com/download/all/desktop-esr/ as pick the 64-bit or 32-bit Windows then language then click on [Download ESR 115] The web whatsapp site a few months ago made it so you needed Firefox 115 or later.