This is carried out in the toolbar. Invocation of this option persists any changes you have made to the organization within the operational database. Any outstanding validation issues are reported in a dialog and you may not proceed with the save until they have been resolved.
If the organization contains any changes to its hierarchy nodes, parallel organization node user groups are created, modified or deleted to ensure that one user group per hierarchy node exists within the system. Such user groups are named ‘Organization – Node – [Node Name]’. They exist to allow users to be linked to specific organizational hierarchy nodes, thereby limiting access to objects associated with that set of nodes (or linked nodes, if applicable).
For further information please see the User Group configuration documentation.