Big problems with sync of icloud-iphone-ipad. help!

You can't back up an iCloud account. You would have to back up each data area separately. But there's no need to do this. Just go to Settings>iCloud and tap Delete Account, if prompted about what to do with the iCloud data choose Delete from My iPad. Next, sign back into the old iCloud account and turn iCloud data syncing back to On to sync the data back to the iPad. Then go to Settings>iCloud and tap Delete Account, this time choosing Keep on My iPad when prompted. Then sign back into the account he wants to use and turn data syncing back to on, and when prompted, be sure to choose Merge. This will upload the data to the new account.

You're welcome. You should have been prompted but you may have made the wrong choice when you were. When you delete an account you are prompted about whether to keep or delete the iCloud data on the device. If you choose Delete, the data would have been removed. Also, if you do keep the data on the device, when you set up the new account you are prompted about whether or not to merge the data with iCloud. If you choose Don't Merge, the data in the iCloud account would have overwritten the data on the device, effectively deleting the data. That's why it's important when you delete the account to choose Keep, and when you turn on data syncing with the new account to choose Merge.

You're welcome.