How do I make the dashboard beep when a booking comes in?

In Notifications you decide three separate things: whether the on-screen alert appears, whether a tone plays (you pick which one and at what volume, and you can test it) and whether you want browser notifications, which reach you even with the dashboard closed.

You also choose when to be alerted: only new bookings, cancellations too, or nothing.

Browser notifications are enabled per device and the browser has to allow them. If you blocked them by accident, only you can re-enable them from the padlock next to the web address: for security reasons, no website can ask you again on its own.

Turning alerts off does not switch anything else off: bookings keep coming in, you just stop seeing the pop-up.