Rules that survive compression
- Three words on the thumbnail, max
- Face + emotion beats abstract graphics for most niches
- One accent color that is not YouTube red
Canvas setup
Use 1280×720 in Poster AI Creator. After export, shrink to 160px wide in your OS preview. If the title vanishes, regenerate with fewer words and higher weight.
A/B without guessing
Ship two thumbnails on comparable videos. Keep prompts identical except headline verb: "Fix" vs "Avoid."
