IOS – iPhone: Is it possible to gift paid app to another user

Apple has an article called iPhone and iPod touch: About backups that has information about what and where iTunes stores things. These folders are portable and you can move them from mac to mac, PC to mac. I have had no issues when using different versions of iTunes - especially if the "receiving" computer is as new or newer than the "sending" computer. If you can update both before the transfer, that would probably be ideal.

iTunes places the backup files in the following places:

• Mac: ~/Library/Application Support/MobileSync/Backup/

• Windows XP: \Documents and Settings\(username)\Application Data\Apple Computer\MobileSync\Backup\

• Windows Vista and Windows 7: \Users\(username)\AppData\Roaming\Apple Computer\MobileSync\Backup\

After the transfer completes, the backups should show up in iTunes and you can restore your phone form it. Do read the article iTunes: How to move your music to a new computer if you are not certain

1)your friends itunes account was probably registered on your phone when you synced with the computer.

2) you can only be synced with one itunes account at a time. your problem might be that your synced with your friends account so any app that you download with your account wont be able to sync any apps unless you change it to sync with your account(which will delete all apps not purchased with your account.)