Thanks for posting your question about managing your check stubs in QuickBooks Online (QBO), @cmiqbs.
For now, only the payee information, amount, and transaction date will be printed in QBO. Account number and other banking details will not be printed for security purposes. You'll need to use a pre-printed check stock with your banking details already added to it. You can either ask your bank or purchase it in the Intuit Market Place.
If you need the account number to be processed by the bank, it's recommended to use pre-printed voucher checks that include the account number. These checks can be obtained directly from your bank or ordered through Intuit.