In Groove only the account owner has access to the billing settings for the account. The billing section is found under Settings > Company > Billing.
The billing summary lists all of the active users that you are being billed for and at the bottom of the list you can choose between the monthly and annual plans.
On the right side of the page is where you enter your credit card details and billing address.
Under manage account the current owner can transfer the account ownership to one of the other active users.
All of the account invoices can be viewed and downloaded/printed from the invoices section.