On some research I have done for the last couple years from studying in school. Even though I failed my English class almost every year doesn't mean I didn't learn anything from it. Theme was one of the pieces of literature that I didn't excel at to be honest. I tried my hardest to figured when you can tell the theme of a story or movie.
Honestly, movies are easier at trying figure out their theme then books. For books, you need to use more auditory focus to find the theme, but when watching a movie you need equal amount of visual and auditory to truly see the theme of that particular movie. Books take more time then movies, but they go more in depth. It adds more details and ideas to theme of a book then someone watching a movie. Honestly I prefer movies only for enjoyment and books for figuring out the structure that the author had put the time into for the reader to