@Ousmane SOW Thank you for reaching out to us, issue description is not quite clear, as per my understanding you want to configure this as a single tenant app, would request you to check the manifest file/configuration under app registration section for the application and look for signInAudience attribute https://learn.microsoft.com/en-us/azure/active-directory/develop/reference-app-manifest#:~:text=signInAudience%20attribute this value in manifest file defines whether single tenant or multi tenant app.
Also you need to use the endpoints configured under app registration/overview/endpoints section, if my understanding of the issue is incorrect, we can connect offline and discuss further on the same.