I’ve marked an invoice as paid by mistake on QB mobile but it has not been paid yet ,I want to send a reminder to the customer. How do I get it back in unpaid invoices ?

Hello Jasoncooke2002-y, Welcome to the Community! First you would need to remove the payment from the invoice. If you click on the invoice payment in the customer transaction list and delete the payment. The invoice will go back to being unpaid. Any questions let us know.