There is no .deb or upgrade for your software ?
You don't have the last release of Firefox, Thunderbird, Peazip, Seamonkey, Netscape etc...?
The new release has stability or security patch and you would like to fix it
You would like to have it with only a few clicks and without compiling ?
1) You must have a directory where you are allowed to write : I choose my home directory and mkdir 'bin'
2) I download the french 'tar.gz' package
3) Extract it in your /home/bin directory
4) You get now something (for example for firefox /home/bin/ifrefox or for thunderbird /home/bin/thunderbird)
5) You can add a new entry in the start menu or in the panel ; for the mozilla softwares, linking on the '.sh' file (ie. firefox.sh, thunderbird.sh)
6) Reading the Mozilla installation instructions for Thunderbird you will see that your previous settings will be used, you loose no data except : under Thunderbird 188.8.131.52 the data folder is .mozilla-thunderbird and 184.108.40.206 is .thunderbird