The negative amounts on your sales statement indicate that a customer has an outstanding balance or has overpaid, Mbunt.
To confirm this, I recommend running a Customer Balance Detail report. This report provides a detailed breakdown of each customer's balance and any open invoices, including their dates and amounts.
The report also summarizes all open invoices to show the total amount owed by your customers, which should align with the Accounts Receivable balance on your Balance Sheet.
Additionally, if you are still unsure of the cause after reviewing the transactions, I suggest consulting an accountant to identify and correct any errors in your accounting records.
If you’re referring to something else or have additional questions about your sales statements, feel free to comment below.