With Apple’s release of iOS 4 just around the corner, you might be wondering how to stop iTunes from automatically updating the system software on your iPhone or iPod Touch. This is particularly important if you’ve decided to jailbreak your device.
The reason for this is that a software update will overwrite your jailbreak, and you likely won’t be able to redo it until the jailbreak community comes out with a new hack. Once there’s a jailbreak method available for the new software, you can go ahead and upgrade.
The good news is that iTunes will not update your device without your permission. In fact, it doesn’t even have an auto-update option. It will, however, automatically check for software updates. If it finds a software update, you’ll then be asked if you wish to install it.
If you don’t even want it to check for updates, simply open the iTunes preferences, make sure that you’re on the “General” tab, and uncheck the “Check for new software updates automatically” option.