type New message keyword in the search in the Language section of your admin panel: www.yoursite.com/admin/languages you'll see ***New Message*** among the search results. Change it's value. 

I tried but it is saying No values with ***New Message*** keyword. Thanks in advance.

type not ***New Message***, just New message

Thank you. very much. :)

One request per topic, please. Do the search on the forum it's been discussed a lot of times. 

ok got it. thanks.

Topic was moved from Bug reports and troubleshooting.