If the XAMPP server
is running for the moment, stop XAMPP server.
Follow these steps to change the port number.
Open the file in following location.
[XAMPP Installation Folder]/apache/conf/httpd.conf
Open the httpd.conf
file and search for the String:
Listen 80
This is the port number used by XAMMP.
Then search for the string ServerName and update the Port Number which you entered earlier for Listen
Now save and re-start XAMPP server.