Tapping a customer in the Customers screen lists all transactions for the customer; that is all sales to the customer, all payments the customer has made, and all credits you have given the customer.
To enter a new payment, sale or credit, tap Add a new transaction. To edit or carry out an action for an existing transaction, simply tap the transaction.
A greyed-out transaction indicates one or more of the following:
The transaction appears on a statement. For these, you are not able to change information such as the transaction type or amount. If you need to correct an amount you previously entered, you can edit the transaction from the Statement screen.
Opening a transaction gives the reason why it is greyed out at the bottom of the transaction form.
For further information, please refer to: