I'll make sure to clear up any confusion you have about the invoice payment appearing as negative in the All Sales tab, Dsosk.
When a customer pays an invoice, the system displays the payment as a negative amount. It's normal and indicates that the payment is reducing the outstanding balance on the invoice. I've added a sample screenshot below for reference:
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I've got an article for you about managing your sales and customers. Feel free to utilize this page: Topics about your company's income and customers.
If you find anything else confusing while using QuickBooks, please don't hesitate to post again. I'm always available to provide the information you need.