Entering an opening balance when the company isn't in history mode

Post a General Journal entry to update the opening balance in Sage 50 Accounting.

Go to Company, then General Journal.
Enter the Source, Date (previous year fiscal start date) and Comment.
Choose the account you want to enter the opening balance for.
Enter the balance as a debit or credit as appropriate.
Choose the account or accounts you want to use as the other part of the transaction.
Enter the appropriate amounts.
Post the journal entry.