1. It needs to have a default of a black background with white text. This is standard best practice. I've tested the colors and find #242424 for the background and #fffff0 or #fffffd for the text work well for multiple disabilities.
2. One of the captions suddenly has a background and I have no idea why because Background is not checked. And even if I check it, the captions won't appear with a background I selected even though it's at 100% opacity. (Tried 0 too.)
3. When the captions transition from one to the next, they overlap briefly. Which doesn't make sense because the timeline does not overlap. They're next to each other.
4. One of the captions shows up highlighted the whole time (No. 6). I don't know why. There's nothing special about it. It shows up whether playing or not.