how is this done in 13.2? some sys file isnt it?

uhm, well in 13.2 it is not so simple to change for everything to use the new browser you like. (From my findings at least) So good news! With v14/15? we are trying to make it simpler for the end user. However I am not sure the fixes will be able to carry through and update of 13.2 yet. Now as far as I know to set the browser default you will need to
1) set via update-alternatives (update-alternatives --config x-www-browser)
2) set via mime type in /usr/share/applications/mimeinfo*
3) set via mime type (if there) in ~/.local/share/applications
4) change all referances in the menu from iceweasel to your browser (or remove iceweasel and symlink"iceweasel" to"browser")
5) change all referances in the CC like #4

and probably more that I cannot remember off the top of my head.

Maybe someone else who has more commonly switched their browsers around can comment (and I can see if I need to fix up the new defaults program for V14/15 __{{emoticon}}__ )

I think I just installed firefox & then uninstalled iceweasel, but I didn't have a second/third browser option.

thx __{{emoticon}}__