Welcome Susan to the forum.
Is the switch marked cargo light switch?
Here is a link
you should have and a Brochure
& Owners Guide
We really need someone with same coach to answer your question, I will have answers but not all of them, we can do a Newmar search and see what that may tell us, your answer maybe in the first post of this search
All these links I gave you are in the first link I gave you for Newmar Owners sticky.
If that's not enough all the links below in my signature will help also.
Good luck with your new to you Newmar and safe travels.