The account owner is the only user who has access to the billing settings.
The billing section is found under Settings → Billing.
The billing summary lists all active users you are being billed for. At the top of the page you can choose between monthly and annual billing options. You can enter your card details in the lower left corner.
Account Management - Change Owner
If you need to change the account owner, we have a guide that shows you the specific steps to do that here:
Account Management - Invoices
All of the account invoices can be viewed and downloaded/printed from the Invoices tab.