Firefox useragent - changing the string manually

I appreciate there are tools to change the useragent in Firefox, however the plugin needs to be compatible with the version of Firefox you are running and if you have the latest alpha / nightly build etc the plug in might not work.

I had this situation recently where I couldn't get Firefox 2.0.0.3 to run reliably, so I downloaded Firefox 3.0 (Gran Paradiso). All was well, except I was barred from banking sites because my browser ident string wasn't on their authorised list. Silly banks, surely they know that checking the browser user agent via Javascript is more reliable?

Anyway, even if I did have a compatible user agent switcher plug in, very few of them include the latest released version of the browser in the pre-programmed list which again makes it hard to convince the banks that you are running the latest stable software.

So here are the instructions on how to set the user agent string yourself on Firefox

Goto the browser address bar:
Enter
About:config

Right mouse click to get the context menu and choose New->String from the menu.
Enter

general.useragent.override

As the preference name.

Then enter this as the value

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.8.1.3) Gecko/20070309 Firefox/2.0.0.3

For the average user running Windows XP, this should be fine to get past the pedantic banking sites who don't have a robust way of checking the browser version.