This information is coming from the properties. You can see those on a per project basis in the "Property Manager" (I've attached a picture of my "View">"Other Windows">"Property Manager" but Assimilater has pointed out that the location may not be consistent across Visual Studio editions.)
In your Property Manager window you'll need to find your projects properties. Find your project and open the folder for the configuration you wish to modify. Right click on: "Local settings (specific for all projects in the directory)" and select "Properties".
From there you can edit "Common Properties">"C/C++">"General"'s "Additional Include Directories". Anything added here will show up in the "Inherited values" of your projects "Additional Include Directories" dialog.
I've validated that this information is consistent on Visual Studio 2008, 2010, 2012, 2013, and 2015.
You can read a more in depth piece on how to use properties here: http://blogs.msdn.com/b/vsproject/archive/2009/06/23/inherited-properties-and-property-sheets.aspx
