New users accounts are stored in the container "Users" by default. Because Group Policy can not applied to this container, this may not be a desirable place to put user account. A scenario where this may be a problem is that you have more then one administrator who can create user accounts. Proper procedure says that all new user accounts must be moved to an OU after creation. This individual did not complete this task and the required Group Polices for user accounts in your organization do not get applied. This can create a undesired security vulnerability.
Below is the procedure to change the default location for new user accounts to the OU of your choice. It is copied from the reference link below.
1. Log on with domain administrator credentials in the z domain where the CN=Users container is being redirected.
2. Transition the domain to the Windows Server 2003 domain functional level or newer in either the Active Directory Users and Computers snap-in (Dsa.msc) or the Domains and Trusts (Domains.msc) snap-in. For more information about increasing the domain functional level, click the following article number to view the article in the Microsoft Knowledge Base:
3. Create the organizational unit container where you want users who are created with earlier-version APIs to be located, if the organization unit container that you want does not already exist.
4. Run the Redirusr.exe file at the command prompt by using the following syntax, where container-dn is the distinguished name of the organizational unit that will become the default location for newly created user objects created by down-level APIs: