How to remove old version Firefox and how remove temp file for Firefox in Ubuntu ?
How to remove old version Firefox and install new Firefox 19.0 in Ubuntu?
If you have Synaptic installed simply type in the search-field Firefox and mark it for complete removal (this action will include removal of your hidden files and translation files if installed).
Then open the Softwarecenter and type Firefox click for installation, this action will give you the latest Firefox (19 at this moment) installed.
For eventual translations of FF re-open Synaptic and search for firefox-locale-xx (xx is the language of your choise) . Use this only when translation is required.
Synaptic is a very handy program so if you don't have it first install it via the Softwarecenter.
just run these commands in the terminal:
this command will update firefox to version 19 (laatest now) as for temp files, ubuntu manages them nicely and they'll be cleaned automatically for your convenience.