Some balances in the Edit Accounts window - History view can't be changed
The History view of the Edit Accounts window enables you to change account balances only for months in the fiscal year preceding your conversion month (that is, the month you began using MYOB AccountEdge to keep your records), with the exception of the month that immediately precedes your conversion month.
If you want to change the balance for the month preceding your conversion month, you must do so by updating the account's opening balance using the Account Opening Balances window or the Profile view of the Edit Accounts window. (Use care in making changes to your accounts' opening balances, however; these changes will affect your accounts' balances in future months, as well.)
Amounts for your conversion month and later months are updated automatically as you enter sales, purchases and other transactions in MYOB AccountEdge.