You can mark an invoice as paid even if the customer pays in cash in QuickBooks Online Solopreneur, Jennifer.
You can manually mark the invoice as paid and record it by using the Record Payments.
Here’s how:
- On the left side of your screen, click Get Paid. Then Invoices.
- Choose the invoice you want to mark as paid.
- Click Record Payment.
- From the Select an account dropdown menu, select Cash.
- Then, click Save.
You can also read this article for more information on managing invoice payments, including how to record partial payments in QuickBooks : Record invoice payments.
Let me know if you have any more questions about handling invoices and payments in QuickBooks. I'm here to help anytime!