You need to set your latest message in your chat room to be read. You can see documentation below:

Javascript: https://documentation.qiscus.com/chat-sdk-javascript/message#update-message-read-status
Android: https://documentation.qiscus.com/chat-sdk-android/message#update-message-read-status
iOS: https://documentation.qiscus.com/chat-sdk-ios/message#update-message-read-status