Firefox is a web browser as it does not have a firewall nor a antivirus scanner.

Mozilla Firefox is the only web browser still supporting the old eol Windows 7, 8, 8.1 with Firefox 115 ESR as Firefox 116.0 and later requires Windows 10, 11 to run. https://support.mozilla.org/en-US/kb/firefox-users-windows-7-8-and-81-moving-extended-support

An option is to perhaps dual boot with a Linux distro to use current versions of Firefox from Mozilla though that may be a bit technical.

Chrome, Chromium dropped support of Windows 7, 8, 8.1 with last version being 116 release back in Aug 2023.

I have been unable to sign into my bank account online (on this computer) . Been prompted to update my browser (Chrome, Safari, Forefox, Microsoft Edge), I checked my Firefox version, says up to date.

Is the bank account with Chase? as they are looking for Firefox users to have Firefox 128.0 ? or later.

You can try to change your Firefox version number to fool the Chase site.

1. In a new tab, type or paste about:config (with a colon) in the location (address) bar and press Enter/Return. Click the button accepting the risk.
2. In the search box in the page, type or paste forceVersion and pause while the list is filtered
3. Double-click the network.http.useragent.forceVersion preference to display an editing field, and change the value to 128 or 140 then press Enter/Return or click the blue check mark button to save the change.