YouTube change thumbnail on the phone (samsung) without a laptop?

I created a Youtube channel a few days ago with 2 videos. I know from experience that the thumbnail makes a lot of attention about the calls, as I wanted to change the thumbnails was not, not even in the desktop version on Chrome.

Now my question can somehow get that on the phone to change that?

https://play.google.com/...ator&hl=de

I have the app but that is not synonymous thank you