Between rate and use, there are icons. Those are what change the coin you're looking at in the charts. As for the lending amount, as far as I can tell, it will only go as low as the lowest offering -- so there was likely a flash crash. If you watch rates, for example, even though a rate may show 0.1%, people will often throw coins up at 0.05 or so. Doesn't make sense but they do it.