How do I stop my Mac from syncing my whole library to my iPhone? Every time I plug my phone into my Mac, iTunes tries to synch hundreds of songs to my phone. If I just let it, it uses up all the available storage. I can't seem to find any menu option anywhere to stop the auto synch or to reverse the direction.
This is fairly straightforward to disable. Follow these steps:


Launch iTunes
Go to iTunes > Preferences
Select the Devices tab
At the bottom, uncheck the Prevent iPods, iPhones, and iPads from syncing automatically
Exit Preferences


Let us know if this doesn't resolve your issue.