Most of the animated backgrounds consist of multiple tracks. To extend them, you need to double-click on the group, which opens a view on each track. Select all the tracks (Ctrl/Cmd+A), and drag the endpoint to the right.
Double-click outside the tracks to fit the group to the track length. And click Back to the main timeline to exit the group.
How to Extend Backgrounds
or drag and drop files
Mira
Comments
GLENDAN ROBERTS
After following all of the steps, I was able to extend the background, however no matter how many times I double clicked (off track) it always went back to it's original length. Now, I suppose it only allows so many tries, because it won't let me extend them any more.