Creating a separate apple id/password for a single devise that is already registered

Question

I am having a terrible time managing the family's devices on iTunes.  I was trying to use one apple id and password for all, but when i last synced all of my devices, my contacts and calendar events were all replaced with my 15 year old son's!  I spent 1 1/2 hours with someone at the Genius Bar at the apple store, but with no success.  I am slowly trying to repopulate the calendar and contacts on my iPhone and do not want this to happen EVER again, so I am attempting to set-up a totally separate account for my son's iPhone on another computer in the house.
What is the process for creating a new apple id for the one devise WITHOUT changing the entire account? (not sure if it matters, by my son's phone is the iPhone5, and mine is the iPhone4S)
PLEASE HELP!!!

Answer 1

You have to delete the existing iCloud account, then set up a new one with a different ID.  To do this and migrate your data to a new account, first decide which device(s) will be changing accounts and which will be keeping the existing account.  On the one(s) that will be changing, if there any photos in photo stream that are not in the camera roll that you want to keep on the device you'll need to save these to the camera roll first, by opening the photo stream album in the thumbnail view, tapping Edit, then tap all the photos you want to save, tap Share and tap Save to Camera Roll. 
Once this is done, one each device that will be changing accounts, go to Settings>iCloud, scroll to the bottom and tap Delete Account.  (This will only delete the account from this device, not from iCloud.  The device(s) that will be keeping the account will not be effected by this.)  When prompted about what to do with the iCloud data, be sure to select Keep On iPhone.  Next, set up a new iCloud account using a different Apple ID (if you don't have one, tap Get a Free Apple ID at the bottom).  Then turn iCloud data syncing for contacts, etc. back to On, and when prompted about merging with iCloud, choose Merge.  This will upload the data to the new account.
When you're finished migrating the device(s) to the new account(s), if you have any merged data that you don't want on your device(s) you will then have to go to icloud.com on your computer and sign into each iCloud account separately and manually delete the data you don't want (such as deleting the other device's contacts from your account, and vice versa).