29/10/2021
Here's something that could help in designing your custom thumbnails.
So you need to know if your Thumbnails are suitable for all devices and different sized screens? Here's how you can preview them along with your title to make sure your video will surface congruently on YouTube.
This free site is brill for just the job.
https://thumbsup.tv/
Now you can check how your thumbnail previews on all devices and sizes.
If you really want to hone your YouTube thumbnail game to match your audience, go to YouTube studio > Analytics
Select ADVANCED MODE (Top right of the user interface)
Along the top menu select more to find Device Type
Here you'll see the device (mobile, desktop etc) that your audience consumes your content.
Go back to Thumbsup.TV and check for those sizes. Can you easily work out what's going on in your thumbnail. Can you read the text if you have it on your thumbnails? If not. Start again! It would be a shame if a great video gets no views because your thumbnail isn't getting clicks.