I need to change my credit card information. How do I do so?

You need to go to the Amazon web site. Select "Account & Lists," "Your Account," then "Payment Options" to update your credit card information.

we dont have access to your personal or financial accounts you would need to open your account or profile to change your information

Log in to your account for apple store. go to accout
edit credit card info. Change or remove your payment information from your iTunes Store account...

what do you mean ! Change information to a Bank , or Information to someone else, Just call whoever you want to change info , then change it.

1. Go to Manage Your Content and Devices.
2. From Settings, select Edit Payment Method below Kindle Payment Settings.
3. Select the desired credit card information, or add a new card, and then click Continue.
4. Enter the desired billing address, and then click Continue. You will be taken back to the Kindle Payment Settings page where you can view your edited 1-Click payment method.

http://www.amazon.com/gp/help/customer/display.html?nodeId=201252570

Had that problem too. Call the Kindle (Amazon) service number.

http://www.amazon.com/gp/help/customer/display.html/?nodeId=200127470

Amazon com Help Kindle Support

You need to change the number on the Amazon site. Go to Amazon, your account, Manage payment options, will probably ask you to verify log in info, Click on Add payment method, You MUST set new card as default. That may be what you missed. I did it the last time I changed mine. There should be an option to delete old numbers.

In itunes in the top left hand corner click on you account name and log into your account then when presented with your account information click on the edit button next to your payment information and you will be able to update your credit card information. Hope this helps.