Distribution of a part payment across sales invoice items

I’ve received a part payment for an invoice which has 3 sales invoice items. The system seems to have allocated a percentage of the part payment across all 3 sales invoice items. In this situation the payment is for 2 sales items and is part payment for one. I’m wondering if it’s possible to override the automatic allocation?

You can manually allocate how you receive your payment. In one receipt, you can select 3 invoices under Accounts Receivable and enter the amount received for. The Sales Invoice for the part payment will have a balance due.

If you want to allocate payment against specific line item within an invoice, then that’s not possible. If that’s what you require, then you need to issue separate invoice for each line item.