In a multiple users scenario you should use the Administrator User account only for administering your system.

Recommended startup steps:

1. Log in as Administrator

2. Change the default password of the Administrator

3. Create the new User accounts in the Users viewer

Each User has its own private Group and Role which ensures that object created and owned by them remain private.

If an Administrator add others to a User's private Group then those users will gain access to the User's private objects

Administrators can setup special Groups and add Users to control object sharing.