I have created a site in SharePoint 365. I am the owner. I have full control. Yet when I do specific actions (e.g., change the navigation settings) I am told that I must request access. I do this and the request comes to me. I approve myself to have access but nothing changes. I am still unable to complete the action. SharePoint still prompts me to request access.
Here are my permissions as originally set up by default with the site.