How to adjust the duration of the video on a slide?

On the artboard click “Pages” in the lower-right corner of the screen to see the pages layout menu. Then, head the cursor over the slide and click on the triple dot menu click “Duration”. On the scale adjust the length from 6 seconds (standard page length) to 15 seconds or type in your preferred page length (up to 300 seconds) into the box:

If you type in the number that is more than 300, the system will automatically adjust it to 300 seconds.