To change the aspect ratio of your video:
Navigate to the video you wish to change.
Select the drop-down menu next to the video title, located on the top left of the screen and select the video size option.
Select the aspect ratio you want to use to change the video ratio.
Edit the elements on the screen to fit your new aspect ratio.
See the video aspect ratio documentation to discover all aspect ratios available.
Notes:
To learn more about the Zoom function, check out the How do I Zoom in on the Video Canvas? article.