You can change your file's thumbnail inside the File Manager either in your Library or your Hub.
Step 1 - Find your media file
Inside your Hub editor, open your Hub's Content tab to locate your file.
From here, click on the file to open the File Manager.
Step 2 - Change your file's thumbnail image
Once inside the File Manager, click Thumbnail to change the thumbnail image of your media file.
Click ⬆️ Upload and select the image saved on your device to upload.
The recommended size is 1280 x 720 pixels or 16:9 aspect ratio.
To ensure best practices, avoid uploading a thumbnail with special characters (such as %, $, #, @, etc.) in its name. We recommend removing these characters from the file before uploading it