You may wish to stop anyone in your clinic from voiding or editing invoices prior to a certain date (e.g. lock all invoices created prior to 31st December) but still allow payments.
To do this, go to "Settings" then "Invoice settings" as below. In the section "Lock invoices until".
Select the date from the date picker as below:
The date selected will then appear as below. Please note that this action is not reversible. Once a date has been inserted into the "Lock invoices until" field it can not be removed:
Once this is done, if you try to edit an invoice which is dated before the date you entered above, you will see a notification as below "Invoice is locked". (You will also not be able to void this invoice):