How do I put a minus / credit on an invoice please

Hi billsheartwood,

You can follow these steps to apply a credit to an invoice:

1. Select + New.
2. Select Receive payment or Receive payment.
3. Select the customer, then the credit and the invoice.
4. Select Save and Close.

You can also refer further to this guide on creating adjustment notes or delayed credits, and this article on handling customer credits as required. Feel free to reply if you have further questions as we're here to help! 

-Kass