Go to Billing in your account. This opens a secure billing portal where you can:
Change plan or switch between monthly and yearly
Cancel your subscription
Update your card
Download invoices and add tax details
Upgrading
Takes effect straight away, with a prorated charge for the rest of the month. New credits are available right away.
Downgrading
Takes effect at the end of your current billing period.
Cancelling
You keep your plan until the end of the period you've paid for. Your projects and live sites stay; paid features such as AI changes and connecting new domains stop.