Configure appropriate organization-wide defaults
You’ve been asked to create a custom object for tracking projects. The Project custom object records should only be visible to the owner of the record and users above the owner on the role hierarchy. Create the Project custom object and then create an organization-wide default for the Project object to accommodate for this use case.
The custom object must be named 'Project' with a resulting API name of 'Project__c'.
 What I have tried is that I made in organization's sharing settings  for object Project below settings
Object: Project
Default Internal Access:Public Read/Write
Default External Access:Public Read Only
Grant Access Using Hierarchies:Tick yes
 Got below error
"Challenge Not yet complete... here's what's wrong:
The organization-wide default for the Project custom object was not configured correctly"

Please guide me