There are 2 cases for editing purchase invoices:
(1) In the case of credit purchases
(2) In the case of cash purchases
To edit the credit purchases:
Navigate to Bookkeeping>>Purchase>>Purchases>>Action-drop-down>>Edit.
To edit the cash purchases:
We can edit the cash purchase transaction only if we delete the payment transaction. For deleting the payment transaction, please navigate to:
Bookkeeping>>Bank>>Dashboard>>Select the bank account (or) Cash in Hand account>>Action drop-down>>delete.
Now we can edit the transaction by navigating to Bookkeeping>>Purchase>>Purchases>>Action-drop-down>>Edit.