The procedure on how to change the blue color of the Facebook chat box is pretty simple. Every Facebook user can undertake it with ease. See: How to View Messages History on Messenger
How to Customize Facebook Chat Color
To change the color of the Facebook chat box, do the following;
1. Open your Facebook account
2. Click on the Messenger symbol at the top right corner of any Facebook page. That will open the list of the people you chatted with.
3. To open the conversation or chat box, you’ll need to click on the name of the person whose chat color you wish to change.
4. Next, click on the gear icon at the top right corner of the chat box to initiate a drop-down menu
5. Click change color from the list of the menu that appears
6. You’ll now need to pick or select a color for the conversation. Do that and the color change will be applied ASAP. Bear in mind that everyone in the conversation will see it.
You can also change the conversation color in the Messenger app. See: Steps on How to Delete or Clear Notifications on Facebook
How to Change Messenger Chat Color
To change the messenger conversation color, do the following;
1. Open your Messenger account
2. Click on the name of the person whose chat color you want to change
3. Click change color at the right side of the of the chat interface
4. Finally, choose the color of your choice from the pop-up box
That is how to change the color of your Facebook and Messenger chat box.