How to test on iOS5.1 Xcode Simulator when you also have iOS6 simulator installed.

I recently uploaded my first corona app to the AppStore.  It seems to crash on iOS 5.1.  I cannot see a way of testing on iOS5.1 when all my devices is already iOS6.  I have Xcode 4.6.2 with iOS 5.0, iOS 5.1 and iOS 6.1 simulators installed.  When I do a build in corona for the Xcode simulator, simulator with version 6.1 starts up with the app.  If I switch to the older iOS version on the simulator by Hardware/Version it does not have the app on the version.  I have tried a couple of things, but cannot seem to test iOS 5.1 on simulator.  Can someone please help?