[Ajax Search] How to set up to make searching with 2-characters-word possible?

1. How to set up to make searching with 2-characters-word possible? i.e. searching just with ‘DW’ – The default seems to be 3-letters.
2. I feel stuck when there is no search result, showing up ‘Not found! Try another keyword.’ and cannot dismiss unless remove whole the keyword. – I think just click outside exit ‘d be better.
 
Thank you for the nice Plugin 🙂