Having a good thumbnail can matter a lot when promoting your project to studios or other places. It can also be cool to keep an aesthetic or style of how you make your thumbnails. FAQs: Tips from @ashetrees : Having vibrant colors or good artwork in your thumbnail will make people curious and want to click it. It is the impulse of the viewer. It is how you get people to view your project. Don't make it excessive though because that can make people confused. Read the tips from this project if you still need help with colors: https://scratch.mit.edu/projects/778558464/