You can set the threshold for how many previously used passwords will be disallowed from being utilized again with the USERS MAY NOT REUSE THE PAST N PASSWORDS option found under the Password Policy section on the Settings > Security screen:

This will specify and enforce how many of the most recent passwords cannot be reused.

Ex) If the value is 3, users cannot reuse the previous three passwords when changing their password. The default value is 10. If set to 0, the user will not be able to reuse any of the previous passwords.