If you need to change the supplier on a recorded bill, here's the fastest way to do it:
Find and open the bill to be modified and save it as a recurring transaction.
Delete the original bill. Need a refresher on deleting transactions?
Go to Lists > Recurring Transactions, select the recurring transaction you just created and click Use Recurring. A new purchase transaction is displayed.
Select the correct supplier for the transaction and ensure all other details are correct.
Go to Lists > Recurring Transactions, select the recurring transaction then click Delete.