Welcome to Bullet!
On the editing of bills, invoices etc. you should be able to edit them (click on the one you want to edit in the overview screen, then click on the ‘Edit’ button at the bottom).
Sometimes we will stop you from editing an item. For example, if the VAT period is already marked as paid, or if you have already received payment for the invoice or paid a bill.
In the case of already having received payment, you can delete just the payment asocciated with the bill/invoice you want to edit – edit it and make your changes – and then record the payment again.
What does the error message say when you try to edit the invoice/bill?