Proposal invoices

I’m having trouble with
How can I change/adjust an invoice associated with an accepted and partially paid proposal invoice? For example:

  1. Client accepted a proposal.
  2. I sent part 1 of 2 invoices, which was paid,
  3. Now I need to make an adjustment to the final invoice.

How can I adjust this invoice? It is not showing up in the invoices tab, only the proposals section, where my only option is to first send what is now the WRONG invoice to the client before being able to edit it.

Working in
Wix Editor

What I’m trying to do
I want to be able to edit the 2nd proposal.

What I’ve tried so far
Searched through the proposals and invoice tabs.