Updating the appsettings.json from a .Net Core controller

I'm trying to update the appsettings.json from a configuration controller and can't seem to find a sample or post relating to updating the file.

I'm passing in the IConfigurationRoot to my controller and updating it with the view model data.  I thought when I updated the settings, the sync between memory and the file would be automatic, however this is not the case.

Any information is greatly appreciated.

Thank you.