If you want to keep track of which messages you’ve read and which ones you haven’t, you can do so on your iPhone by marking them as “unread.” Here’s how:

  1. Open the Messages app on your iPhone.
  2. Tap on a message to open it.
  3. On the top right corner of the message, tap on the three lines icon (it looks like a triangle with an “x” inside it).
  4. On the new screen that pops up, tap on the “Unread” button.
  5. The message will now be marked as “unread.” ..