All transactions can be changed or deleted except where Allocations is On and a transaction has been allocated to an Invoice or Payment.
The Change and Delete facilities should be used with care in the accounting software.
If, for example, a VAT Return has been made for a given period, changing amounts or deleting transactions would mean that an manual adjustment would be required in the next Return to account for the discrepancy.
Similarly, you should avoid making changes to Lodgement or Bank Payment amounts for any month/period for which you have already successfully reconciled your bank account(s).
In the case of voided cheques or cancelled Purchase/Sales invoices you may prefer to change the entry to show zero amounts rather than delete the whole transaction. This approach has the advantage of allowing the system to show a record of all reference numbers rather than having gaps in reference number sequences (e.g. a missing cheque number).