>There is a way to do it via the windows registry...
>
>HKCU\Software\Microsoft\Office\15.0\Outlook\Options
>
>Once there - , create a new string value called DefaultPath ...and put the path you want in for it's value data.

Thanks, I have created the entry as follow:

See attachment

However, if I restart Outlook, create a new message and click on Attach file, I am redirected to C:\Users\MyUser\Documents.