The option for header in the theme settings only lets me change colour, logo etc. Is there anyway to change the information that is already written. (photo given below) So I want to be able to access that and be able to like, remove/add widgets of my own choosing, add text box etc.
You can find the options to hide of show this or that element in the Header. Theme Settings > Header. As for the header menu, you need to create a menu in Appearance > Menu and assign accordingly.