Confusion with Apple IDs

While I look for a single point where this is explained, or someone else beats me to it and puts a link, I'll try to briefly summarize:

Apple ID: it uses an email account, which could be any email account, to identify yourself with Apple Services. The Apple ID stores your personal data, address, payment method, phone number, backup email and phone number, if you provided them

Keychain: in short, it's a password manager (it does more things, as keeping certificates, public and private keys, etc., but)

iTunes: media store for music, tv shows, movies, etc. To log in and purchase, you use your Apple ID

App Store: app store (no music, only apps). To log in and purchase, you use your Apple ID

iCloud: a service which Apple provides to sync some data across your devices. For example: mail accounts, bookmarks, music, photos, files, backups and system data (like Keychain data). To be able to use this feature, you log in with your Apple ID.

For example: you browse a website using Safari in your Mac, register your email and password, and Keychain stores it into your laptop, so you don't have to type it again. If iCloud is enabled for Keychain in both your Mac and your iPhone, when you open your iPhone, you can log in to that website because the passwords were already stored.

Or you take a picture with your iPhone, and if iCloud is enabled for Photos, the picture will be available in your Mac without downloading it, or sharing it with yourself, or syncing via iTunes: iCloud does that for you.

Unfortunately, it is not possible to merge accounts, therefore the warning. You can create a Family and include your accounts there. See the link below [1] and whether it's worth the effort for you.

What the above displays is that you are indeed using one Apple ID to sign in to iCloud (my educated guess is that is the new one created in the Apple Store) and another different Apple ID to sign in to the iTunes & App Store.

On your Mac you have a username and password to log in, and then an Apple ID. You can create as many other users you want in the Mac and use the same Apple ID in all of them.

Think of the Apple ID as a credit card: you may have many, they all belong to you, and you use one for the grocery store and another for the travel agency.

Given your setup, and also bearing in mind that I'm not official Apple Support, I would set the iPhone iCloud Apple ID to the same you are already using for the iTunes & App Store and on the Mac. But I understand the confusion and that "if it works, don't touch it".

[1] If you want to know how Family Sharing works and how to set it up, see

Family Sharing - Apple Support

Just be careful which account do you use, because you can only use one Apple ID at a time. To see which one you are using now:

• In a Mac: iTunes > Account > the first two lines will display your name as entered in the Apple ID and the email account
• In an iPhone or iPad: Settings > iTunes & App Store > Apple ID

First, make an offline backup of your files by going to both the Desktop and Documents folder and copying the files to an external drive.

Then, you can disable iCloud Drive in System Preferences > iCloud.

It will prompt to remove or keep your documents already stored in iCloud Drive, tell it to keep a copy.

After that, you should be able to sing out of iCloud and sign in with the other account, and if you want, enable iCloud Drive for this account.

I cannot stress enough the importance of having a backup of everything: contacts, notes, etc., that might be only in this account and not in the other, so in the worst case, you can still sign in with the new account and restore all those contents.

EDIT I forgot to mention that if you are not sure or not comfortable or you think it is too risky, let an Apple Genius assist you during the process: Genius Bar Reservation and Apple Support Options - Apple

Please post a screen shot of the pop up , hide your mail address or personal info before posting , for taking screen shot use command , shift and 4 key on the keyboard , use preview app to hide , see this method to how to hide

Click on edit and delete , then click on file - save , after that quit preview .

The big difference from your Mac and the iPhone when it comes to iCloud Drive is that it stores actual files you are using: all those in the Desktop and Document folders. If you remove from your Mac without a backup of those folders, you will lose those contents.

Maybe you can check if you miss any file while it is a 100% or simply copy those files to another location like an external drive.