There many reasons why you want to disable the itunes auto sync with the connected devices. My reason was that, I wanted to be sure, that I always have a good working backup on my computer.

What happens if you have mistakenly deleted/changed some importent settings on you phone and then want to recover them via sync? Yes you connect the iPhone to your pc, and iTunes automatically sync you wrong data from the phone to the pc. Of course you can stop this, if you are fast enough. But isn´t it better to be sure to don´t have this problem?

On Windows:
- Open iTunes - Click Edit - Click Settings - Click Devices - There you will find the option to disable the auto-sync (you have to activate the disable 😉 )

On a mac with OS X

• Open iTunes
• Click the iTunes menu
• Click Prefences
• Click Devices
• There you will find the option to disable the auto-sync (you have to activate the disable 😉 )

That was is it! Now the sync is only done if you really click the sync button. Do not forget to do this from time to time.

One last warning: This disables also the auto sync to all other devices like an iPod.