XAMPP MySQL password setting (Can not enter in PHPMYADMIN)

Question

Firstly: I am cannot entering PHPMYADMIN at "localhost:80/phpmyadmin/". Because when I install MySQL server mysql-5.5.36 with Username :root and Password : HamdunSoft . After that when I enter localhost:80/phpmyadmin/ it show me a message like below .

"Error MySQL said: Documentation 1045 - Access denied for user 'root'@'localhost' (using password: NO) Connection for controluser as defined in your configuration failed. phpMyAdmin tried to connect to the MySQL server, and the server rejected the connection. You should check the host, username and password in your configuration and make sure that they correspond to the information given by the administrator of the MySQL server."

Now I want enter my Phpmyadmin though I have setup two MySQL server one in xampp, another mysql-5.5.36. I have searched it in net but the content was not helpful sufficiently. How can I set the password in xampp before login in phpmyadmin .

Another different issue is: XAMPP Apache server was saying : port 80 is being used by some one. I solved it by stopping Skype. But again having this types of problem. I think like Skype another software is using port 80. I want to use any port with Apache as I wish. It may be port 80 or 81 or 82. If any other process is using my desired port I want to replace that and give that port to Apache.