No and Yes.
You can not modify the Device Dropdown. The path to the My Documents, My Video, My Pictures, and so on and received from Windows. They are special location and Windows will return the path that Windows has configured for the current users for those folders.
But you if you configure windows so that you want the default "My Documents" folder to be some other path then that path will be used.
You can do that by right clicking on the "My Documents" (or any of the other special folders) and select properties and then in one of the tabs shown you can then move the path to another location. This is a Windows change and will affect all programs that ask windows for the path to that special location.
