These instructions will show you how to use the Plesk admin panel to change PHP versions. Start by logging into Plesk.
1. Log into the Plesk admin panel and select Tools & Settings from the options on the left.
2. Select Updates and Upgrades from the Plesk column. 
3. Select Add/Remove Components
4. Use the + next to Web hosting to expand the column, then do the same for PHP interpreter versions. Change your desired version to install and click continue.
The Plesk installer will run. Once complete, you will be able to use your chosen PHP version.
Note: You do not necessarily need to remove previous versions of PHP. Doing so may cause conflict with various native Plesk applications such as Horde.
