Enable Auto Lookup

When Enable Auto Lookup in the User Preferences is checked, it will enable automatic searching in the drop down boxes.

 

 

For example, you click the drop down arrow of a line item in your Invoice.

 

The drop down box will automatically look for that line item in the drop down list.

 

 

Also, even when you just start typing in an item, you would notice that the drop down box is filtering items containing the character you type.