After you have installed the STAMP add-in, you can find captioning options within the Video Tools Playback tab on the Ribbon. Do remember though that the Video Tools Playback tab is a contextual tab which appears only when you have a video clip selected in your presentation. Before adding captions, you need to insert a video clip in PowerPoint.
To learn more, choose your version of PowerPoint. If we do not have a tutorial for your version of PowerPoint, explore the version closest to the one you use.
Microsoft Windows
Video Captions using STAMP in PowerPoint 2016, 2013, and 2010
Tutorial Code: 18 03 03
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