In my SharePoint Online site, I have multiple pages with the File Viewer web part. When the page is loading, a thumbnail of the file is being displayed for a few seconds.
If the file is a video, the thumbnail that SharePoint displays is a random screenshot of it, like below. I would like to have the ability to change that to display a more corresponding image.
If the file is a document, like a PDF or a word document, I have a blurry image as a thumbnail which is displayed for a few seconds until the page is fully loaded. I would like to be able to change the size or the thumbnail itself because this is confusing and looks like an error for the user.
I have tried to change the thumbnail by creating a “Thumbnail” column in the document library and changing the path there, but SharePoint seems to ignore the set value. I have also tried to change it with PnP with the command