如何让Nginx使用替代PHP版本？

I have an Ubuntu web server running Nginx. I was runngin PHP 5.5.30 and I installed PHP 5.6.23 using the following commands:

1) sudo apt-add-repository ppa:ondrej/php
2) sudo apt-get update
3) sudo apt-get install php5.6

The installation is under a new path from the previous verison of PHP (/etc/php/5.6/). When I run a phpinfo() command from a web page I still get it running under the old version of PHP (5.5.30) - how do I get Nginx looking at the new installation?

p.s. When I run php --version from the command line it show PHP 5.6.23 ! p.p.s My nginx.conf file contains fastcgi_pass unix:/run/php/php5.6-fpm.sock;