When you copy and paste objects between scenes with different durations, you can opt to adjust the object to the destination scene's length or to stretch the scene to fit the object's animations.
1. Select the object you want to copy to another scene.
Notice this scene is has a duration of 8 seconds and will be pasted into a scene that lasts 5 seconds.
2. Right-click or click the Edit button in the top bar.
3. From the drop-down menu, select Copy.
4. Select the destination scene and right-click or click the Edit button. From the drop-down menu, choose Paste with animation.
5. You will see a pop-up message indicating that your object is longer than the destination scene.
You can choose here if you want to extend the scene to fit the object length (in this case it would change from 8 seconds to 5); or if you want to shorten the object and all its animations to fit the scene's length.