You're probably seeing this because you want to make your caption a heading which should stay on the page.
There are more types of text that you can add to your scenes. Basically, they help you to add multiple pieces of text in a scene that can appear at the same time in different positions and styles. Much like seeing a heading that stays always while other captions and labels play alongside.
You could choose to make them a bumper. Bumpers stay on the screen for the entire duration of the scene. Currently, they must be set to captions.
Captions come and go. Bumpers stay.