In earlier versions of iMovie, you could relatively easily import still pictures and alter their duration to create slide show. However, in the latest release, iMovie 10, this ability seems to have disappeared or at least moved. If I import a series of pictures (PDF format), I can use 'Adjust' to see a duration of the form '1.0 s of 0.9 s'. I can type in the '1.0' part but not the '0.9' part, and changes are not reflected in the movie. In particular, I want to set durations of several seconds or even minutes: how do I do this in the latest version?
⌘-click on all the pictures that you want to adjust the timing of in the timeline.
Go to Window → Show Adjustments Bar or press 3.
Select the info button on the adjustments bar.
Enter the duration into the box on the right and press Enter.
This will change the duration of all the selected clips (or in this case, pictures).