what is the difference between cancel approval, rejection and versions in oracle

I need to know is it the standard behavior in CPQ that their can't be changes on the lines (Quantity , discount ,etc) after sending for approval even for the approver should the approver cancel approval make the changes and submit it again then accept it for him self or their is another way

also for the rejection the fields are open again for changes as I think the Quotation returns to the in progress step is their a way to re enter the approval cycle or do I need to make a version and submit it again after changes