Firstly, I updated and upgraded the whole system because the last time I did it was about half year ago ^^! so …JK! JK! lol
$sudo apt-get update $sudo apt-get upgrade
Then, download the latest version of firefox for linux mint from this link: https://www.mozilla.org/en-US/firefox/new/
Unpack it inside the Downloads folder:
$cd ~/Downloads/ $tar -xvf firefox-56.0.2.tar.bz2
And then follow step by step from the instruction in this link: http://www.lauradhamilton.com/how-to-upgrade-firefox-on-linux-mint
In stead of using the name firefox33, remember the version we have now is firefox56 which means changing every line containing “firefox33” to firefox56.