How to get a gaming livestream thumbnail to refresh and show random screenshots?

Thinking about starting livestreaming on YouTube and I've noticed that other gamers who I have watched are able to have random thumbnails from in game. I did a test using Streamlabs and OBS but the only thumbnail that I saw was my channel's default art or else a customized thumbnail when it comes to OBS. But I want the stream to show the thumbnail from random intervals when it refreshes.

Is there a setting that I'm missing when it comes to the thumbnail so that it will show in game screenshots and not just my channel's default art?

I would be doing a mix of pc games as well as using remote play for my Xbox for playing if it helps with a solution.

Thanks in advance.