Invoice not showing Paid In Full?

When I mark a invoice as paid it its sill showing not paid in the New sale section…

It’s showing paid in the payment section.

there is no option in Manager to mark an invoice as paid in full. it happens automatically when you receive payment against that particular invoice.
please read the guide and make sure you have followed everything correctly as explained in the section Receipts against sales invoices.

If you are using Accrual accounting the invoice will be included in Sales as soon as you create it.

If you are using Cash accounting it will only be included when you receive the payment

Your screen image does not show enough information to answer any of your question. It looks like it might be a cash sale, in which case there is no invoice involved

Please explain in more detail what you are doing