You can edit the payment date by first opening the transaction - you can do this clicking on the invoice, selecting the payment in the top right hand corner, and selecting the date. You can then edit the date within the payment and save.
THIS IS NOT AN INVOICE DATE IT IS A TRANSACTION DOWNLOADED FROM THE BANK THAT HAS THE INCORRECT DATE AS THE DATE HAS REVERSED AND INEED TO CORRECT IT TO TALLY WITH MY BANK STAEMENT