How to configure base sdk?

Hey guys Ive already installed my game on an actual device (version 4.1), the problem is that when I tried to install it on my iTouch 1g (version 3.1.3) it tells me that it is an old version I tried to build it for other and I typed iOS Device 3.1.3 but it didnt worked.

Any ideas on how to install it on my ipod touch 1g?

Project Settings/Player, iOS Tab, check settings for 'SDK Version' and 'Target iOS Version'