How do I change the color of the text bubbles in the Samsung Messages app?

[BabyGS]

In the native Galaxy SMS app (Messages), there used to be a way to customize the color of the text bubbles prior to Marshmallow.  It seems like this option has disappeared.  Does anyone know how to change the colors of the bubbles in Marshmallow on a Galaxy S7 Edge? I want to do this without root access, of course, and I would prefer to do this in the native app like I used to be able to do rather than having to install a 3rd party SMS app.  Thank you in advance for any solutions.

[Tidbits]

I believe only way to change them is to change your theme. You can only change the background.