As someone said above, sometimes the overlays episode provides dont always fit the background properly.
You scale your overlays in the same way you would spot direct your characters.
The first step I would recommend is to figure out which overlay belongs to which zone. For example, you might have one overlay in zone 1, and one in zone 3.
Add your zone 1 overlay first and scale/position it so it fits where you would like it. Then think about whether you want your characters to be behind that overlay, or in front if it. If you want them to be behind, make sure your overlay is layered at for example, layer 2, and your character is layered at layer 1. (It doesnt have to be these specific numbers but that’s just an example)
Then I would repeat this for each overlay using @cut to zone 3 (as an example) to then see zone 3 and place my overlay for that zone using the method above.
Overlays can be tricky, but you really are best to try and work things out yourself with other peoples advice rather than asking them to do it for you, as if you come across this issue again, you will be able to resolve it yourself.
Try my beginners guide and see if it can help you: Lesson 8: Inserting Overlays - Google Docs