Please help with the invoice no: 1759This invoice has been saved as fully paid but it was a mistake. Only £240 is paid from the total

Hello Aylinonsu-gmail-, welcome to the QuickBooks Community. We can certainly guide you through amending the full payment on the invoice to be a partial payment instead. If you go to the customer> go to the paid invoice and select edit> in the top right where it says 1 payment click on that> click again on the date that populates> then you will be on the payment. Click into the box with the received amount and enter the 240.00> make sure that the invoice number selected to have the amount paid is the correct one (if you have multiple open for that customer it will show multiple) then save and close. You will get a warning about editing but you can ignore that. That will record the partial payment. Any questions let us know we'd be happy to help further.