There are several ways to take these actions.
In the message list, you can act on a conversation by swiping it left and right. This can also be set up directly from Settings.
Also in the message list, you can long press on a conversation to enter edit mode. From here, you can select as many messages as you want and take action on all of them by using the options in the top right corner of the app. Mark unread, flag, move, and other actions can be found by tapping on the vertical bar.
After you open a conversation, you can take action on it by using the options in the top right corner of the app. Mark unread, flag, move, and other actions can be found by tapping on the vertical bar.
You can also take action on a single message in the conversation by tapping the horizontal bar to the right of the header of the message you want to act on. From here, you can mark that message as read or unread, you can flag or unflag it, you can delete it, or you can reply to it.
