In B2Brouter, the equivalent state of “Paid invoice” is the state “Closed”.
To change the state of an invoice, you need to open the specific invoice from the list.
Once you are visualizing the invoice, you will see a light-blue menu just on the top of the invoice. Inside this menu, you have different actions, click on the option “Mark as” and a drop-down will appear.
Select the state “Closed” and B2Brouter will consider the invoice as a paid one.