how to set firefox default browser in gnome

["Yuwen Dai" <yuwend@gmail.com>]

Dear all,

What's the correct way to set firefox default browser in gnome? 

There're several places you can click a link:
1. in Emacs wiki mode.  I add these these lines in ~/.gnome/gnome-moz-remote:
[Mozilla]
filename=firefox
NEEDS_TERM=false
NREMOTE=ture

so the default browser is firefox.

2. in thunderbird, when I click a URL, it still opens epiphany.

3. in command line of gnome-terminal, it also opens epiphany.

I used 
update-alternatives --config x-www-browser

to set firefox as the default browser, but still can not solve  2 and 3.

Best regards,
Dai Yuwen