Payment received from customer did not reduce customer invoices

I assume you have you entered the staff member in both Managers “Customer” and “Employee” tabs?

How exactly are you doing this? A “Transaction” type “Payment” with a positive entry to their “Employee” clearing account and an negative entry to their “Customer” clearing account, resulting in a net about the Employee/Customer actually receives this month.
As was suggested here

Manger is designed to rarely need journal entries. I’m not sure this is the most reliable method for routine business operation actives.

When posting screen shots please include Managers screen title and the “Bread crumbs”. These are located at the top of each page in Manager and show what screen you have captured and how you got there. Examples of which are
For an Employee
title Employee

For Accounts receivable
Accounts receivable

For a journal entry
Title journal entry