Why Does My Scene Do This?

Hello all,

When I first load my game, my Main Menu scene looks perfectly fine. The mountains are the shade of white I like and everything is bright and just the way I made it in the scene view, like so:

But when I go to a new scene (like About, or Options) and come back to my Main Menu scene, my mountains get darker and everything else in my scene gets darker and looks all weird, like this:

Does anyone know what is happening and how I can fix it? If you need more information or more pictures just let me know and I can provide that. Thank you! :)