Slip Entries Printing out of Sequence

Question

Can someone please help me with this huge problem? Each time I enter my slips and print out the bill, my slip entries are shifting out of the sequence that I want them to appear. So then I have to go back and retype the entries in the proper order, and when I print the bill out, the same thing keeps happening over and over. Please help shed some light on this problem for me.

Thank you.