Searching persons in address book

Hi All,I Have a question regarding the searching of people from address book when sending mails and selecting person manually from address book.

When i click new message select person from address book ( directory) it is always find person starting with last name .

like my name is IMRAN JON ,when i write imran system never find my name but when i write my last name ( JON ) system finds my name.

is there any procedure so that i modify searching from last name to first or middle name.

i am using notes 8.5.1 basic client .

thanks