How to edit the credits in a trailer

I am using iMovie for Mac 10.0.9 and have produced a trailer. Now I wish to remove some of the "directed by", "written by" elements in the Credits section I see no way to access a timeline to edit the text boxes. In an earlier version of 9.x I could select the text items and edit them. Looks like Apple have taken away this capability. Does anyone know any way that I can remove these elements?