The focus keyword is only guiding you, to be honest I dislike the traffic light system because it encourages users to narrow their views on what they should be focusing on. It does nothing other than guide you.
If you are happy with the keyword focus for one keyword, simply change it to another keyword and optimise for that that phrase, changing back to the original phrase to ensure your edits have not hindered anything.
Just remember you are writing for real people, not search engines.