You have to scroll through the external views holding down the R3 and pressing the circle. Not got a controller in front of me but I think that's how it is.
External views can by cycled is holding down right stick while tapping D-Pad right. Internal views can by cycled by holding down right stick and using D-pad left. Right stick and circle is "contact signaller" I think. You can also set a preferred default external camera (mapped to clicking right stick) in options.
