Adding text onto images or video files inside of iMovie is not always easy with the limited selection of options. By using Google Drawing you can easily add text over your video. Just create the text you want in Google Drawing, using the large variety of fonts and formatting, leave the background as it was and then download as a PNG file. You can then drag that PNG image into iMove, remove the Ken Burns effect and make it a picture in picture setup, and then arrange the text where you want.
Watch the video below to see how to do this.