I'm trying to understand your answer and I'm having difficulty.  I'm thinking that you don't understand my question.  It is essentially is this:  I need to fix the negative numbers that are currently in the "total quantity" column of my "Item List".  That column needs to have all zeros in it.  I'm hoping there's an easy way to do this rather than going in and fixing over 600 invoices.

I need to fix a mistake I made for apx 6 months. If there truly is no easy fix, I will go in and change those 600+ invoices.

All of the other information in my question was to provide a bit of background information as to what led up to this mistake being made and to convey that the problem leading up to the mistake had been fixed, including getting rid of an incompetent CPA who could have told me about the mistake when it was a 2-month problem instead of a 6-month problem.  You seemed to think my background information was my question and never actually answered my question.

You state "You don't have to use QB and "inventory Items" to use QB to Track inventory."  I know that now, I didn't know that when I started in May.  The company I worked for previously did track inventory through QB and I assumed (wrongly) that this company did also.   You then go on for a long time about inventory management and that is not helpful information.  Not to mention it's contradictory - first you state I don't have to track it then go on to tell me how to track it.  Our inventory is tracked through a different program and the appropriate entries are made at the appropriate time.  No one is "just throwing values at the data".  I don't need QB to track the inventory.

You then seem to think I needed to know how to fix the invoices because you state "Perhaps they also had a Noninventory Version of what they sold, before you arrived. Or, they used Service items. Look at older sales, to know what they listed in the past."  Already did that, that is why I stated that procedures had been changed.

You then quote my question back to me and never actually answer it.

But I thank you for your input.