You need to sign in to do that
Don't have an account?

Security model
I have 5 users and they are associated with different different profiles. And everything set in that way so that no one can see each other records. Also owd is set as private . But one of them available to view the records why so
He might have "View All" or "Modify All" permission.
Details:
https://www.forcetalks.com/salesforce-topic/what-does-view-all-and-modify-all-permission-do-at-object-level-in-salesforce/
Role Hierarchy also might be the case.
Hope It helps, Please mark it best answer so that it can help others in future.
Thanks!