Saving Content Considerations
The following portal registry classes have Save methods:
Content reference links
This means if you change a folder, you must save the folder. If you change a folder and only save at the PortalRegistry level, your changes are not saved.
Some classes do not have a Save method. For these classes, you must save the parent object.
If you change a node, node template, or remote portal, you must use the PortalRegistry Save method.
If you change an AttributeValue you must use the Save method with the item that contains the AttributeValue (folder, content reference, PageletCategory, or Pagelet).
If you change a PermissionValue, you must use the Save method with the item that contains the PermissionValue (folder, content reference, PageletCategory or Pagelet).
If you change a UserTab or a SelectedPagelet, you must use the Homepage Save method.