Plesk allows you to customize the Panel Branding, including the title bar text and the logo you and your clients see.
1) To do this, go to Tools & Utilities.
2) Click Control Panel Branding.
3) In order to set custom title bar text, you must first uncheck Use Default.
4) Type your text here.
5) Browse for an image to use for the logo.
6) If you ever want to revert to the default logo, return here and click Default Logo. Click OK.
That's it! Now you know how to customize your panel branding in Plesk.