Create a split-screen effect in iMovie on Mac - Apple Support (LB)

Table of Contents

To change when the split-screen effect appears, drag the split-screen clip in the timeline so that it connects to a different spot in the clip below, or drag it to a different clip. You can also drag the ends to lengthen or shorten it.

To apply the change, click the Apply button Video Overlay Settings button in adjustments bar

Do any of the following:

Set where the connected clip appears in the frame: Click the Position pop-up menu and choose an option.
Add a slide-in transition and set its duration: Drag the Slide slider.
If the transition duration is set to zero, no transition appears.

To apply the changes, click the Apply button in the split-screen controls.