I changed this note “Registering for this site is easy. Just fill in the fields below, and we’ll get a new account set up for you in no time” to my custom note, and i changed “Blog detail” to “Profile detail”. Then i made 2 file : 1) – buddypress-en_US.mo . 2) buddypress-en_US.po and i uploaded both to /wp-content/languages/plugins/ .