How to change a subscription's login info in Plesk
A Plesk hosting subscription has its own login info, separate from your Panel login credentials. This is what you'll use to access your files via FTP, for example. Your Plesk account may have more than one subscription attached to it, and we'll see how to change the settings associated with each one in this tutorial.
The active subscription is displayed under your username on the home screen.
Go to "Websites & Domains". All the options shown on this page apply only to the active subscription.
Click "Web Hosting Settings". This page lets you change your username and password for the current subscription.
Now you can make changes and click "OK" to confirm.
Remember, this applies only to the active subscription. To switch to another subscription, click the links under your login at the top right. Note: if you do not have more than one subscription on your account, you will not see this dropdown.
