How do I change the aspect ratio in iMovie on MacBook Air?

Hi,

iMovie 10 has a fixed 16:9 aspect ratio that cannot be changed. When you set the crop adjustment to "Fit" (click the crop tool in the tool bar at the upper right of your screen and select "Fit" from the selection box) a video in 9:16 aspect ratio will display vertically but with black bars on each side of it to make it fit the 16:9 screen. When you export the video it will show smaller because the vertical clip will export with black bars to fit a wide angle screen in a vertical orientation.

You can work around this by using the rotation rectangles of the crop tool to rotate the vertical video sideways so that it fills the screen. Then export it in the sideways orientation. Once the exported movie is on your desktop open it in QuickTimePlayer and use the rotating tool to rotate the video right side up. Then save it. Now the black bars will be eliminated and the video will display larger. You can do the same procedure with a 3:4 video.

Another way to export in 9:16 is to create the movie with the New App Preview feature. Go to the projects browser screen (where your projects are displayed as icons) and do a File/New App Preview. A screen will open that looks like an ordinary project screen, except it has fewer options. Import your 9:16 clip into the timeline and when you export it, it will be 9:16 without black bars.

A third way is to export the vertical clip with black bars from an ordinary project. Open and play it on your desk top.Take a screen recording of it by using the Control-shift-5 feature to drag-select only the video portion, eliminating the black bars, so that that screen recording renders only the video portion without the black bars.

-- Rich