Solidworks is shipped with a few material libraries already set up.  One of those is the Custom Materials library located at C:\ProgramData\SOLIDWORKS\SOLIDWORKS 20xx\Custom Materials.  By default this library is read-only and the only way to modify it is by running SWX as an administrator.  The folder can't be changed to 'writable' via windows explorer.  Since this is a 'custom' materials library it seems that SWX wants us to put our 'custom' materials in there instead of in the other libraries.  If that is the case, why do they lock it down and make it so annoying to modify?