How to Update Firefox

For diagnostic purposes please proceed as follows:

Open a terminal window (e.g. by simultaneously pressing ctrl-alt-t)
Copy the following text from this browser window:

uname -a; lsb_release -crid; apt policy firefox

Switch to the terminal window and press the right mouse button, and in the pop-up window that appears select "paste"
Press the Enter key to execute the commands
Then select all contents of the terminal window by moving your mouse with pressed left mouse button across the window, press the right mouse button and select "copy" and finally paste everything into this question document.

If you encounter any problem when trying to follow these instructions, don't hesitate to tell so.

Hello Manfred, thank you for your help! Below is the requested information:

Linux Lappyx1 4.15.0-142-generic #146~16.04.1-Ubuntu SMP Tue Apr 13 09:27:15 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
Distributor ID: Ubuntu
Description: Ubuntu 16.04.7 LTS
Release: 16.04
Codename: xenial
firefox:
  Installed: 88.0+build2-0ubuntu0.16.04.1
  Candidate: 88.0+build2-0ubuntu0.16.04.1
  Version table:
 *** 88.0+build2-0ubuntu0.16.04.1 500
        500 http://us.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages
        100 /var/lib/dpkg/status
     45.0.2+build1-0ubuntu1 500
        500 http://us.archive.ubuntu.com/ubuntu xenial/main amd64 Packages

Support for Ubuntu 16.04 has already ended in April 2021 (except for Expanded Security Maintenance which does not include updated versions of Firefox and similar programs)

You have to upgrade your Ubuntu installation to a supported Ubuntu release, or restart from scratch by installing a supported Ubuntu release (e.g. 22.04 LTS), overwriting the current installation.

I understand, thank you. How could I install a supported Ubuntu release, and keep my laptop's settings intact?

If you want to keep all settings and contents, then you probably better do an in-place upgrade.

I am unfamiliar with how to do this. Do you have any suggestions or resources you recommend?

You can initiate an in-place upgrade to a newer Ubuntu release either from within the update-manager application or by opening a terminal window and issuing the command

sudo do-release-upgrade

for a tutorial see https://ubuntu.com/tutorials/upgrading-ubuntu-desktop