Choose a theme for legibility
A theme should support the subject.
Prepare
Start with the density of the material. A data-heavy explanation needs clear labels and strong hierarchy. A photo essay needs space for the image. Choose a theme after identifying these needs rather than relying only on its thumbnail.
Work through the decision
Use one project to compare themes so the content stays constant. Inspect a title scene, a dense information scene, and a closing scene. Check contrast on both bright and dark photographs.
Review the result
When you switch themes, verify that the facts and asset choices still match the project. Recheck line breaks and crops before a final export; different typography can change what fits in a frame.