After you reply, the thank-you screen shows a personal link to your reply. Keep it: it’s how you change your answer later.
- Open your personal link, or open the invite again on the same phone.
- Tap Change my answer.
- Switch between Coming and Can’t make it, update the numbers or your note, and tap Update my reply.
You can change your answer until the reply-by date. The host’s headcount updates straight away. Anyone with your personal link can change your reply, so only share it with people in your household.