In order to edit the Header, go to the Homepage and hover with your mouse on the Header. Click on it and you will see a popup to Open Global content editor. Click to open the Global content editor where you will be able to edit the following settings:
Upload the logo, define the dimensions of it and the alternative text.
Menu and Socials:
Select the Main Menu and the socials for your header.
Enable/disable language switching in the Uranus header.
Insert a header button that you can configure differently from the main menu.
You can discover more about the Global Content and learn how to edit this on this related article.