This article explains why line items in Order Entry may not sorted by the line number.
It is possible to sort the line items in Order Entry by any of the visible columns. If you have sorted by the description column, or any column other than Line, then when you add a new line it may not appear at the end of the list; The new lines will be sorted as they are added.
To change the sort order, simply click on the column heading. For example to sort by the line number, click on the Line column heading. To sort by the description, click on the Description column heading.
Order Entry will remember the last sort order and use it every time you start Order Entry.