You can add your company's logo via the Organization Settings so that it is displayed on all exported documents (controlled / uncontrolled). The logo is visible on exported documents only.
How to add your company logo:
Go to Settings>Organization Settings
Click on the "Logo"
To add or update click "Choose File"
Select your logo file
Click "Upload Logo"
Your logo will now display on all exported documents.
Your logo file may only be in png or jpg format
Logo size is 1200px X 1200px. If your logo file is larger it will be scaled down, maintaining the aspect ratio.
Additionally, headers and footers on exported documents are uneditable.