I just installed Xcode 6.0.1 (coming from Xcode 5.1.1) and tried to run my iOS app on iPhone 6 simulator for the first time. It builds and runs, but I cannot change its settings
This happened to me, too. It seems that the settings file is not saved at all.
˜/Library/Developer/CoreSimulator/Devices/[GUID]/data/Containers/Data/Application/[GUID]/Library/Preferences
is empty.
I've tried to use plist file from 7.1 simulator, but without any luck.
Downloading iOS 7.1 Simulator through XCode -> Preferences -> Download allowed me to save the settings, but that just for iOS 7.1.