I just am trying to figure out how to change the backgrounds behind text messages. Is there a setting or some app which lets you do this?
Go to the Messaging app and hit the settings button. You will see Bubble style and Background style.
When you select Bubble Style you will see options at the bottom of the screen that you can scroll through (the top option is the look for your outgoing messages, the bottom option is the look for received messages).
When you select Background style there are a few options to scroll through at the bottom of the screen as well.
You could install a 3rd-party app like GO SMS Pro to replace the stock Messaging app. This would allow you to customize the font size, colors, backgrounds, theme, and others.
Go to your messaging app on your front screen or where ever you have it placed and then once you are on it go to the bottom left corner on your phone and tap it and then hit settings and scroll down and it says bubble style or background style and there you go you changed it and you can also change your messaging background