You can add a customer to track your income earned and expenses incurred in QuickBooks Online.
Customers can be vendors; each name should be unique. If you use the same name, append the name by adding "customer" or "vendor" at the end of the name to differentiate the list name.
To add a customer to the QBO account:
1. Click on Sales
2. Select Customers and enter the name, phone number, and email. Update all the contact info as this will enable you to send me emails and invoices and click Save.