Yesterday updated my iPhone 4 to iOS 7. I did that with a clean install. Before that I made a secure backup in iTunes so I could load that backup into my 'new' iPhone. But after I loaded the Backup I noticed that only 30% of my apps was available on my iPhone. Most of them did came along with the backup i creates earlier. I am able to download each app without costs from the app store using my iPhone. But that takes a while. Therefor I thought of using iTunes. But iTunes says: This iPhone is synced with a different library <insert name of my PC which I don't have for about 2 years now>. Do you want to erase this iPhone and sync it with this library? I switched from PC to Mac this year. What is my risk of deleting the iPhone and syncing it with the library on the MBP? I use iCloud (als backup) & iTunes Match. Am I able to use the backup again? Will I loose apps? Are my settings again deleted? Whats to gain and whats to loose with syncing or not syncing with iTunes?