In Clear Books, invoices can be marked as paid with a few clicks using the Quick Pay Method. This feature is enabled in Settings > Configure system > Toggle features
Navigate to Sales > Invoices
Click on the Unpaid tab.
Click on the invoice number of the invoice you would like to pay.
Fill in details of the Quick pay section in the bottom right corner of the invoice and click the Pay button to complete.
This will enter the payment in the bank record and mark the invoice as paid