Tips: How to change the Firefox User Agent?

For some unknown reason, the User Agent from my browser (Iceweasel) It doesn't show me which distribution I'm using specifically in the plugin that we recently activated here From linux.

I have already changed it as you can see, but the question is how did I do it? Simple:

1- We open a tab and type about: config and what I always say, they deceive Firefox / Iceweasel telling them that we won't get involved 

2- Right click on any value » New [New] » String [String] and we write:

general.useragent.override

3- Then we copy the following:

Mozilla/5.0 (X11; Linux i686; rv:7.0.1) Gecko/20100101 Debian Iceweasel/7.0.1

Obviously that is in my particular case. The funny thing is to see what happens when we put things like this:

Mozilla/5.0 (X11; U; Linux i686; en-US) AppleWebKit/534.16 (KHTML, like Gecko) Linux Mint/11 Chrome/11.0.696.57 Safari/534.16

Mozilla/5.0 (X11; Linux:Debian x86_32; rv:2.0b8pre) Gecko/20101011 Opera/10.0

We can try other variants 