A central place to manage all invoice s is the list of invoices, which you reach by clicking Invoices in the top menu.
The list contains the most important information: date, state and amount. If you activate a Final state, an additional column Sent date will appear as well.
Hover over the total bar to see a number of invoices for each state instead of their total amount.
To find a specific invoice, type in its ID (or a part of it) in your invoicing system to Search field. Very handy when you need to set an invoice as Paid
When you click Manage, a detailed page for an invoice appears. From there, you set its state, ID in your invoicing system for future reference and a date when you sent the invoice to your client. It's important to set this date as Workshop Butler helps you identifying invoices which are not paid for a while.