Retain sorted list by parameter Merged

When usine the invoice list (regardless of which one) the invoice list parameters need to be retained - ie - why does it change after every access back to the program default, and not keep the sort parameter. I need the sort by numerical, not the ad hoc mess that the program defaults to. I am the book keeper for a client who uses this program, and this sort ability would save me hours, and save the client money!!