Because of an update to the way Facebook handles sharing, it's no longer possible to share directly to Facebook from iMovie for macOS. Use the Prepare for Facebook destination to save a movie, project, or clip as a video file that's ready to post to Facebook. Then, you can upload the video file to Facebook using a browser.
- Click Projects in the toolbar, then select a movie.
- Click in the toolbar, then choose Prepare for Facebook.
- In the dialog that appears, set the title, description, and more.
- To set the title of the shared movie, click the name at the top, then type a new name.
- To set the description of the shared movie, click in the Description field, then type new text.
- To set tags for the shared movie, click in the Tags field, then type tag names separated by commas.
- To change the resolution of the shared movie, click the Resolution pop-up menu and choose an option.
- Click Next, then save the file to your Mac or another local storage device.
- Using Safari or another web browser, sign in to your Facebook account, then upload the video file.