Can I stop the AI answering certain questions?

For email, yes: there is a switch. For chat, no - and the reason is worth understanding, because it is also the control you have.

Email: in Settings, under Email, choose "writes a draft, and a person sends it". The AI's answer then waits on the conversation for someone on your team to check, edit and send. Nothing is emailed until they do, and a draft uses no AI credit.

The AI only answers from what your team wrote: articles you have published, and answers your team gave on conversations it resolved or closed. It does not know anything about your business beyond that. So the way to keep it off a subject is not to publish an article about it, and to Forget any learned answer about it (Knowledge Base, under "Learned from your team") - then it hands the question to a person instead. A question nobody has written about becomes a handoff: the customer is told plainly that someone will follow up by email, and your team is emailed once for that conversation.

What we do NOT have today is a per-topic switch, or a way to turn the AI off for website chat - chat always answers straight away, because a visitor waiting live cannot wait for approval. If you want either, tell us.