I never do that. You could check this setting (enter about:config in the url bar of a new tab): keyword.enabled It should show the default value of 'true'. If it doesn't, click the 'reset' icon at the far left of the setting. When you load that page, you will be given a warning and will have to elect to proceed.

It is "true" already. Keywords work properly. When I use a keyword I want to doesn't appear "Search with DDG or Google".

Thank you for answer.