Here's a sans photo you can use and there's a link.
https://commons.wikimedia.org/wiki/File:SansUndertale.jpg
Copy that and paste it on Option 1. Then, just edit the photo and your thumbnail is ready.
Here's a sans photo you can use and there's a link.
https://commons.wikimedia.org/wiki/File:SansUndertale.jpg
Copy that and paste it on Option 1. Then, just edit the photo and your thumbnail is ready.