How to update Mozilla Firefox web browser on 64-bit Ubuntu 12.04 LTS in a safe, secure, reliable, efficient and easiest way?
You should find out what the latest packages available are, by first running:
sudo apt-get update
and then install the latest firefox:
sudo apt-get install firefox
Or you could install the latest "everything" with:
sudo apt-get upgrade
Ubuntu should have an updater (don't remember exact name) that checks for and asks you about installing (or optionally automatically installs) newer packages/software. Is yours not running or set to keep quiet?
And there's also apt-get dist-upgrade that upgrades Ubuntu to a newer release, but it's traditionally less reliable than a fresh install.
Download the Latest Firefox version from here
Move this folder to /opt/
Open your terminal and type "./firefox"
Voila! Your New Firefox Version is running.
If you want to make this the default browser first go to /usr/bin and rename the previous version's Firefox executable to firefox-old and then move the new Firefox executable in /usr/bin