Message options can be accessed by clicking on the carrot menu that appears when you mouse over any message.
Messages that you send have 8 options: unread, edit, delete, pin, star, copy, reactions and info. See our articles on pinned messages, starred messages and message read receipts for more information on how these tools work.
Adding a reaction will allow you to add an emoji inside the message bubble you've selected. The reaction will be visible to anyone who has access to that message.
You can only edit messages that you have sent. If you’re an admin you can also delete the messages of any other user. Non-admins can only pin and star the messages of other users.