Question: How do I change the color of messages?

[AymanAliS]

Hi, Love the theme, but right now the messages(not mine) are a dark red/purpely color which I don't like, is there any way to change this. I see that the colors are different in your screenshot when in mine each groupchat has it's own colors instead of varied in one and I would love something like that.

Here are some examples of what I mean