Currently, when entering invoices, the 'customer' field allows you to start entering the customer name.... and as you do, it presents the customer names meeting what you have entered.
The problem with the current search is it is not able to find customers which have your typed letters anywhere in the customer name.
i.e. If your customer is "L P Potters Ltd" and you enter 'Potters' in the search box, it will not find the customer.
The consequence is that I often find duplicate clients are created because my staff don't know the exact client name.
The same applies to searching for suppliers when entering purchases.