You can "announce" things like messages you've sent and received, polls you created, and events so they permanently appear at the top of a chat.
To announce messages:
1. Tap and hold the message you want to announce.
2. Tap Announce.
To announce polls:
1. Tap "+" at the bottom of the chat screen.
2. Tap Poll and then the poll you want to announce.
3. Tap Announce > OK.
Note: The Poll feature is available in group chats.
To announce events:
1. Tap the menu icon at the top of the chat screen.
2. Tap Events and then the event you want to announce.
3. Tap Set as announcement > OK.