You can change the version of PHP for any site like this:
1. Login to cPanel using the steps mentioned in https://secure.lightningbase.com/index.php/knowledgebase/6/How-to-Access-cPanel.html
2. Click on "MultiPHP Manager" under Software.
3. Check the box next to any domains you want to change
4. In the drop-down towards the upper right, choose the PHP version you would like. There will be some labeled alt-php and others labeled ea-php. Please choose ea- versions as standard, these will use all of our chosen PHP modules and settings.
5. Click 'Apply'
The change will take place within a few moments.
We recommend checking your site thoroughly after the change to ensure everything is running well, as compatibility of various plugins/themes can vary across PHP versions. If you run into any trouble, the version can be changed back instantly using the above process, and don't hesitate to contact our support if you need assistance.