upgrdae from 6x15 to 6x16

Have ran the necessary security upgrade and ran update.php the site is fully functional once again. The one issue I am having is that it has chaged my php verison down to 4.4.9 from php 5.1

I am a newbie so is there an easy way to resolve this. The upgrade ran no problems at all, sites and files directory uploded after new file loaded. Chagned memory limits back in .htaccess file . Should I have ammended anythign else to ensure it used the same verion of php before I ran the uprade. I did not receive any error messages. All but some of the modules are running, apart from the modules that require php 5.1 i.e. imageapi, etc