To update the billing details for your Intruder subscription, just head to Account (bottom left of your portal) > Billing:

Any updates will be reflected on your next invoice. (It's not possible to amend invoices that have already been issued unfortunately as they're managed by a third party payment platform).

Just hit the 'Switch to annual' button:

And then once you've checked the information, just press 'Confirm and pay':

It's not a problem, though it is worth noting that you will miss out on preferential pricing; if you're okay with that, just pop the team a message via the chat bot and they'll walk you through it. 👍