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All the fields in the grid section are for informational use only and cannot be edited. To unapply one or more transactions, select the transaction(s) from the grid section and click Unapply from the toolbar. Unapplying transactions updates the Customer Balances accordingly and the unapplied cash receipts / credit transactions are displayed in the Apply Documents list view, where users can re-apply the transactions.
See also Voiding AR Transactions.