iCloud 
View or change your iCloud payment information
You can view or change your iCloud payment information, such as your credit card number and billing address, on your iOS device, Mac, or Windows computer.
On your iOS device
Go to Settings > iCloud.
Tap your iCloud account email address at the top of the screen.
To change your billing information (such as the credit card expiration date or billing address), tap Payment Information.
To make other changes, tap the item you want to change.
On your Mac
Open iCloud preferences, then click Manage.
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Click View Account, then enter the password for your iCloud account.
If you entered your password recently, you may not be asked for it now.
Click Change or Edit next to the information you want to change, then follow the onscreen instructions.
On your Windows computer
Open the iCloud Control Panel, then click Manage.
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Enter the password for your iCloud account, then click View Account.
If you entered your password recently, you may not be asked for it now.
Click Change or Edit next to the information you want to change, then follow the onscreen instructions.
Click Done.