1.plug in iPhone 1 2.follow prompts to update software, or do so manually by selecting your iPhone tab in the library column, and clicking the "check for update" button. 3. Unplug iPhone 1 when done. 4.Plug in iPhone 2, (if it tries to sync it, slide the slider on iPhone 2 to stop syncing). 5.follow prompts to update software, or select the iphone's tab in the library column, and click on the check for update button (you may have to scroll down to see this button).