The billing and subscription information will come up automatically (after you log in to your account) if:
- the trial version is already expired and you haven't entered your credit card information.
- the credit card details aren't up to date.
You can already enter your credit card information once the Subscription page is displayed.
On the other hand, here's how you can update the details:
- Click the Gear icon in the upper-right corner and select Account and Settings.
- Select the Billing & Subscription tab and go to the QuickBooks section.
- Update the Payment method.
- Save the changes.
You can refer to this article for additional information: Update Payment Method for QuickBooks Online Subscription.
If you're referring to something else, any additional details would be much appreciated. Thank you in advance!