Hi Can someone advise me? I have accidentally marked one of my invoices as paid. How do I undo this as I have discovered that the client hasn't paid thanks Polly

Hello Polly, 

Welcome to the Community page, 

What you will need to do is go into that invoice and onto the received payment then just delete that received payment, to do this if you click on more at the bottom then delete. Once you have deleted the received payment it will then reopen the invoice for you so when they do pay it you can then just click on receive payment again.