Modify searches via Firefox search bar

Information: Firefox provides a Search Bar to allow quick searches. But you can't easily edit the search engine parameters.

Intention: To edit the Google search in the Search Bar to use 'verbatim' mode (aka 'work properly' mode).

Method: The account here (under 'How do I customise a search engine in 30 seconds') is correct. But an additional step is required: Firefox secretly caches the Search Bar configuration in two files in the profile directory, search.json and search.sqlite. Changes made to (eg) google.xml in the searchplugins directory are not picked up if they don't match these two files.

The solution is to (with Firefox closed) delete search.json and search.sqlite. Firefox will rebuild them, incorporating your changes, next time it starts.

Incidentally, to achieve the original intention the addition to google.xml is

<Param name="tbs" value="li:1"/>

(apologies for the misleading original title of this post)

Btw, here's a precised copy of 'How do I customise a search engine in 30 seconds' in case it gets DMCAed by the Nazis:

Open the searchplugins folder located inside the Firefox installation directory. Open the file google.src with a text editor like notepad and make a simple change in the following line
action="http://www.google.com/search"
change this to..
action="http://www.google.co.in/search" or
action="http://www.google.es/search"

With Firefox Portable you'll find the searchplugins directory in ....FirefoxPortable\App\Firefox\browser , and the profile directory in ....FirefoxPortable\Data .