I just got a new tuner hoping it would be able to register lower tunings such as drop C. It will not pick it up... as soon as I turn my key and try lowering it from E, nothing shows up. This is the tuner I have, any help? thanks guys

alright, so just for the top string 4 times, then the other strings 2 and tune them? Also, What about another tuning? say... drop D?
I don't think that is a chromatic tuner. It will only do standard guitar tuning (EADGBe). Pushing the flat button will work, but sounds like a pain in the ass. You probably want to buy a proper chromatic tuner.