How to add this to chat

I would like that when the user has an unread message an icon or number appears where the unread message appears and that when pressing it and then exit the chat it is no longer there.
I put example of how I have it and how I would like (like whatsapp)

Can somebody help me please??

Hi @ramonroca,

This topic will help you! : Read status changes on ALL screens? Help!

Thank you