After you've raised an invoice and sent this to your customer, the next step, unfortunately, is paying your supplier. When you make payment for the invoice you will need to reconcile the invoice against the bank transaction for it to show as paid.
Please follow the steps below on how to do this.
First up, find the unreviewed transaction in the transactions tab.
Next, click on the transaction and then click on 'Choose a category'.
From the category options, please select the outstanding supplier invoice.
Finally, click on 'Mark as reviewed' to reconcile.
After this, the invoice with show as 'paid' with the transactions linked.