How can I stop auto sync with my iPhone on iTunes?
To stop iTunes from automatically syncing each time you connect your iPhone to the computer, follow these instructions:
1. Open iTunes on your computer.
2. From the top menu choose iTunes -> Preferences (Mac) or Edit -> Preferences (Windows).
3. Select the Devices tab.
4. Mark the checkbox next to Prevent iPods, iPhones, and iPads from syncing automatically.
Now iTunes will no longer attempt to sync automatically every time you plug your iPhone into the USB port.