I'll share the steps on how to correct your beginning balance. The beginning balance is the sum of all the reconciled transactions from your last reconciliation. An incorrect beginning balance means your last reconciliation was off.
You'll want to double-check your opening balance transactions to fix this. Sometimes the opening balance doesn't include transactions that were still pending when you made the account. Here's how.
Go to Accounting, and then select Chart of Accounts.
Find the account on the list. Then, hit Account history.
Search for the opening balance entry. It should have “Opening Balance Equity” in the Account column. Make a note of the date and balance.
Check for transaction that we're not included during your previous reconciliation and then reconcile them.