Each of your username/password combinations has a different function when it comes to your servers, sites, and databases.
This username is your email address and lets you log in to ServerPilot, where you can manage your servers, create apps and system users, review your stats and logs, request support, and update your billing information.
The username and password for your ServerPilot account are not the same as those for the SSH/SFTP system users your apps belong to.
The root user and password are usually given to you by your server provider when you first set up your Ubuntu server.
The root password is used when you first connect your server to ServerPilot and then can be changed immediately after.
Never use the root user when installing apps. If used incorrectly, root will break your server.
A system user is an SSH/SFTP user created in ServerPilot to install apps and move files to your server.
The username and password for the system users your apps belong to are not the same as those for your ServerPilot account.
Your MySQL database name, username, and password are created in ServerPilot and are individualized for each app.
You use these credentials to connect your database to your app during your app's installation and setup, and you also use this combo to manage your database through phpMyAdmin or Adminer.
These username/password combinations are used to log in to their specific PHP apps, such as WordPress, Magento, or Joomla. They are often created during the app's installation and setup.