What happens next?

How to change chat colors and emoji in facebook messenger 
Open the conversation in messenger that you want to change colors for. 
You can change the chat color for any of your messenger conversations. The new color will replace the conversation header color as well as the chat bubble color.

Choices:
 a). Tap the conversation that you want to change. The facebook messenger icon will be at the top of the page..
 b). Tap the settings app on your device to bring out the session menu. Tap settings, scroll down and tap messenger..
 c). If you set this color to lighten certain settings, this will prevent members from leaving messages with the same settings. If you set a darker color or what is called a " medium blue ", the conversation will be colored blue as well..
 d). The changes will be visible to everyone in the conversation. The color change will only be visible in messenger; it will not apply to messages viewed through the facebook website..
d).