Could you try the steps in this article: [[Change your default search settings in Firefox]] If that doesn't work, could you explain the problem in more detail? For example: * In the Default Search Engine selector, DuckDuckGo is not listed as an option * In the Default Search Engine selector, DuckDuckGo does not stay selected when I close and re-open the Preferences page * DuckDuckGo is assigned as the Default Search Engine, and the address bar shows "Search with DuckDuckGo" when I'm typing text into the bar, but the results come out on a different site * Something else...