Blog Sign up Mail reflecting wrong information

Note :
I have created a dummy account for testing the service while i have found the following issue

During sign-up i have chosen my password , and it works well in both for website login and administering the blog operations

Before that i have received the mail from my website after i pressed the activation mail

Your new *********** blog has been successfully set up at:
http://subdomain.domainame.com

You can log in to the administrator account with the following information:
Username: username
Password: ********
Login Here: http://subdomain.sitename.com/wp-login.php

The mail which i received on behalf of the blog information is showing the random generated password which is not selected by me and also the password the email contain is not working

How can i modify the welcome mail with my chosen password