The logo widget is classed as a template widget, which means it is designed to only be used in templates and it’s not possible drag the widget into the site via the Editor. The logo widget can be overwritten by the user but they also have the choice of reverting back to the logo that is set by the code in the template.
The logo can either be changed directly in the visual Editor or by navigating to Manage > Profile. Images can either be chosen from the Images panel or by uploading an image.
The logo widget only has one option of a default logo, which is set with
defaultlogo as shown in the below example:
Much in the same way the image widget works, the image set in the logo widget must be in the the template.