Since I removed rekonq from my system, numerous apps which launch links, e.g. Stackapplet and Thunderbird are not correctly launching links with Firefox, which I am using now as my primary browser.
I need a global way of telling Kubuntu to automatically launch links inside apps with Firefox, I have tried changing file associations but that appears to be irrelevant.

System Kubuntu 11.10 64-bit
@rozcietrzewiacz - your suggested solution can be found here:

Applications > Settings> System Settings > Default Applications. See screenshot in OP, and if you repost your comment as the solution, I will accept it. – ptrcao Oct 23 '11 at 02:03