Hi Sandy,
By default there are 3 columns displayed under the Item dropdown: ParentFullName, ItemType, and SalesDesc. All of the columns are searched when text is entered into the dropdown, but you could remove the description field SalesDesc if you don't want that to be searchable. To do this, open up the screen you are using (as a few screens use line items), then click the Edit button on the Line Items grid. Next, click on Advanced beside the Item field on page 2 of the wizard. Finally, switch the 3rd column to blank (top of the dropdown) instead of SalesDesc.
Please let me know if you have any questions about this.
Regards,
Russell