How to create YouTube thumbnails with Co-Creator
Generate on-brand thumbnails with Co-Creator, refine them by chat or finish them in a design tool.
Generate on-brand thumbnails with Co-Creator, refine them by chat or finish them in a design tool.
Published at October 9, 2026
Designing a new thumbnail for every episode from a blank canvas takes time most podcasters don't have. In this video, John from Cast & Klaar shows how they use Co-Creator to generate on-brand YouTube and Spotify thumbnails directly from a finished recording in Riverside.
He opens Ask Co-Creator from the project, picks a style and a title suggested from the transcript, and gets two options that already match the show's brand colors and template. He then refines them by chatting, for example swapping a word in the text or changing his expression while the rest stays the same. For a final touch, he downloads the thumbnail and adds the episode number in Pixelmator, showing how the AI result can work as a starting point for your own design. It's a quick way to get a consistent starting point for every episode without designing from scratch each time.
After recording, open your project and click Ask Co-Creator at the top of the screen.
Ask Co-Creator for a thumbnail the same way you'd ask a person. Choose one of the available styles. Cast & Klaar use a story style, but it's worth trying a few to see what fits your show.
Pick one of the title options Co-Creator suggests from your transcript, or type your own and press Enter. Co-Creator applies your brand's template style and colors, so every thumbnail matches.
The first time, you'll get two options to choose from. Ask for any changes you want, like swapping a "yes" in the text for a "no" or changing your facial expression, and Co-Creator updates that part while keeping the rest of the thumbnail the same.
Download the thumbnail and open it in a tool like Pixelmator. Cast & Klaar add a rectangle on the right side with the episode number. You can also cut yourself out, change the text, or start from one of the two-person styles and add your own lettering on top.
00:00 Hi, my name is John from CastingKlaar and today I'm gonna show you how we use Riverside to start or generate our whole thumbnail process for YouTube and of course Spotify these days. Once we're done with recording, you go to your project, you open up your project in this situation, episode 737 and all you have to do is go to the Ask Co-creator button on the top of your screen.
00:25 As you can see, if we open it, there's already a couple of things there, but you can just ask it, just like if you're talking to a real person, can you make me a thumbnail? But in which style do you want it? Well, there's a couple of styles you can choose. Just try whichever fits your style the best, I guess. So what we do is we share a story style and then it asks what should be the title.
00:48 Now, as you can see, there's a couple of title options they already give based on your transcript. But for now, let's say, Rear Side FM, You can just make your own one. You press enter and it starts. And the fun thing about this, it will also apply your brands into it. So. It will apply the template style with the anime style.
01:09 It will match the colors based so that everything looks the same. So the first time you ask for a new thumbnail, it will give you two options. As you see, we have two options over here and you can change everything. I like myself in the left picture, but I don't want myself to say yes, but I want myself to say no, for example. I can just ask it, can you replace the text?
01:31 yes for no like this and as you can see here it's used the same thumbnail as before and nothing else changed except it changed the text on my animation to no and because i'm very happy saying yes here and i'm not very happy saying no here it changed my looks as well we do have a trick in place to change it around a little bit and for us make it our own style and give you an example of that as well.
02:01 The first thumbnail is created, you see over here, we wanted to add the episode number on it. So what we do is we downloaded that, we open our Pixelmator software. As you can see, we just opened the thumbnail directly into Pixelmator. So what we did, we added a rectangle over the right bottom side and we just replace it with the episode number.
02:22 Of course, you can do that in any single way. You can... cut me out over here, change the text easily as well. So there's two ways of using the Riverside thumbnails. You can ask the AI to make it for you. And if it's perfect already, that's good. You can then ask them as well if they want to change something. For example, change the yes to a no or change my face to a happy face or whatever.
02:47 If that's out of your possibilities or you think that takes too long or you think you can do it better yourself, totally fine. Just take the picture, use it as a basis and go from there. You can do that with the other styles as well, where you have the two persons already cut out. Take the two persons, cut that in your own thumbnail and use your letters on it.
03:07 The options are limitless, but I think it takes away a good chunk of our time and the results so far, people have been loving it. So this is how you create on Riverside YouTube thumbnails.
More flows by John van Uden (Cast & Klaar) (10)
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