final cut pro
When you add a title to a clip, it still needs to be "rendered," or processed by the computer to permanently add it to the clip.
Sometimes when you add a title, you'll see a green line above the clip, which means you can view the title, but it still needs to be rendered.
Other times when you add a title, you'll see a red line above the clip, which means you can't view the title until it is rendered.
To render a title, in the Final Cut Pro menu at the top click on:
(which will render all the titles you've added to your sequence)
Final Cut then will process your title and permanently apply it to your clip. The time it takes to render depends on how sophisticated your title is. More advanced titles could take up to a minute to render.
When the rendering is completed, the red or green line should be gone from above the clip with your title.