Edit app preview titles in iMovie on Mac iMovie includes a set of titles designed to showcase apps in action, available only for app preview projects. Some of the titles are named to indicate specific functionality:
You add app preview titles and edit title text in the same way as in a standard movie project. For more information, see Add titles in iMovie on Mac and Modify titles in iMovie on Mac .
Format app preview titles In the iMovie app timeline .
To open your app preview in the timeline, double-click it in Projects view .
The text field in the title is highlighted for editing, and the title controls appear above the viewer.
Do any of the following:
Change the font: Click the Font pop-up menu and choose a font.
To choose from additional fonts using the macOS Fonts window, choose Show Fonts (the last option in the Font pop-up menu).
Change the size of the text: Click the Size pop-up menu, to the right of the Font pop-up menu, and choose a font size.
Change the alignment of the text: Click one of the text alignment buttons.
Change the color of the text: Click the Text color well, and select a color from the Colors window.
Change the color of the title’s bar or background: Click the Bar color well or the Background color well, and select a color from the Colors window.
Note: Depending on the title style you chose, some title settings may not be available.
When you’re satisfied with the changes, click the Apply button
Reposition a movable text bar App preview titles with “movable” in the name use a special control to position the text.
In the iMovie app timeline .
To open your app preview in the timeline, double-click it in Projects view .
The text field in the title is highlighted for editing, and the title controls appear above the viewer.
Drag the bar to position the text.
on your Mac, double-click an app preview title in the 
in the title controls.