does ATT ZTE Z831 Android disable the internal storage option
not by design. see SuperThomasLab's answer here (sm partition disk...) to trick it. "mixed 50" corrupted my card (YMMV), but assigning the whole card to internal seems to have worked for me. open the card when you're done and tap "migrate data." card will no longer work as a portable (unless you reformat it as such).