The changes will be visible to everyone in the conversation. [substeps] The color change will only be visible in messenger; it will not apply to messages viewed through the facebook website.
[header] How to change chat colors and emoji in facebook messenger [title] Open the conversation in messenger that you want to change colors for. [step] 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.