debit note/credit note

can i know

Where we can raise Debit/Credit note for Difference in Sale/Purchase invoice and Difference between billed and actual quantity of the invoice, Quality difference

Quantity based or not or both?

If not I would load a new line on the sales order (presuming salues but purchase is the same) for the same quantity right price and another negative line for the same quantity at the original price. Or I would use the credit not function and add a new line.

If quantity use a return order, or do it through the sales order negative line or through the same order new line. Lots of options depending upon what you want to show, process and have.

can u explain detail pls

I have, what do you not understand? Raise a sales order with a negative quantity, raise a line with a negative quantity. Use the function button and create credit note. Create a return order and process it through. All create credit notes ultimately. Are you saying you have not read the manual and have no idea how to process a standard sales order through the system? What details do you require?