One can customize multiple things about how Fenerum issue invoices.
To do so go to "Invoice" tab on the settings menu.
Here you will find different tabs for different invoice settings.
On the general settings you can customize
Logo which will be printed on the invoice PDF
Invoice email template - customization of the templates is described here.
Footers for the invoice. Fenerum supports different footers for normal invoices and for the invoices paid with card where payment will be collected automatically. More on footers here.
Default collection method and default payment terms. This will just affect what will be initial selected values on the forms, but can be changed for each subscription.