Q: How to change the default port number for Apache HTTP Server?

1. Read General Notes
2. Read How to install Apache HTTP Server for HTTP (Web) Server service?

3. e.g. Assumed that new port number is 78

4. sudo cp /etc/apache2/ports.conf /etc/apache2/ports.conf_backup
   sudo gedit /etc/apache2/ports.conf

5. Find this line

   Listen 80

6. Replace with the following line

   Listen 78

7. Save the edited file (sample)

8. sudo /etc/init.d/apache2 restart

9. https://localhost:78