/etc/bin/php alias reverts to different version of php

I have relatively new amazon instance of Ubuntu 16.04 running on fresh versions of webmin/virtualmin. For various reasons I installed php 5.6 and use it on many more sites than php7, which is the default php for Ubuntu 16.04.

I needed to change the default version of php from 7 to 5.6, as I have a script that runs command line, using whatever is at /etc/bin/php. So, I deleted the original alias and created a new one pointing to php 5.6. All that worked great.

However now I am trying to run that script again and have found that the alias again points to php7. The date on the alias is August 1, which is when I was on vacation (IOW obviously not done by me). What would do this, and where do I set the default in Webmin/Virtualmin so that this doesn’t happen again?