This page is a collection of info/ weird workarounds/ tips/ etc. on Firefox.

If you want to add a custom search engine, for example your own searx instance, do the following:

1. Open
   about:config
   (If a warning shows up, klick 'Accept the Risk and Continue')
2. type
   browser.urlbar.update2.engineAliasRefresh
3. Click on the '+' symbol
4. open
   aboutPreferences#search
   (Go to search preferences)
5. Under the Search Engines ListBox there is now an 'Add' button, press it
6. Fill in the Form, add an optional keyword (eg. s search-term)
7. Optional: Change to your custom search engine under 'Default Search Engine'
8. Enjoy (Why do they hide this?)