What files to delete when updating Firefox?

[woflux]

Hello, to update Firefox I deleted all files in usr/lib/firefox and inserted the new ones of the latest version. At first startup Firefox said that it correctly updated from version 12 to 17 but how did it know my previous version was the 12 if I deleted all files before ? what does it check ?

thank you

[Semme]

Cause you've got files in ~/.mozilla.

[woflux]

Cause you've got files in ~/.mozilla.

Do I have to change them too and why it contains same files as in usr/lib/firefox ?

[Semme]

Only for a *fresh* install. While some files may appear similar- they relate to your profile.

Unless there's trouble, a twelve to seventeen upgrade doesn't require a fresh install.