setup centos 7 enviorment
It sounds to me like you are running more than one PHP version on the server. 

Did you remove the current (old) PHP version before adding the new one? Did you restart apache/the server after installing? 

You may need to tell Apache manually to use the new php56. 

check your httpd.conf for the LoadModule definition that defines it and make sure it's referencing the correct PHP installation. 

Centos 7 http.conf location: /etc/httpd/conf/httpd.conf 

Note that any changes you make here require that you restart apache. Also note that changing here has a risk of bringing down apache, so modify with caution.