From your 'My Hub' page (please see below)
You will see a 'Switch To New My PT Hub Now' banner at the top of your screen...
Click the 'Switch Back' button to the right of the banner.
For the new version to be loaded automatically and you will be presented with a quick guide.
you can then notify all of your current clients of the new change by selecting the 'Download The App' button on the right of your screen.
and can also view the email being sent to your clients before hitting 'Send Email' by selecting view email content.
To upgrade simply select the 'Upgrade' button in the top right of your screen...
which will show your available options and outline the price and features for you.
Fill in all the required information and click 'Upgrade Now'