I would like to register a new card but I can’t.

Change, add, or remove Apple ID payment methods

Manage the payment information that you use for the App Store, iTunes Store, iCloud, and more. When you change your payment information, it's automatically updated for all apps and services that you use with your Apple ID.

Change your payment method or add a new payment method.

Edit payment methods

How to change your payment method on your iPhone, iPad, or iPod touch

1. Open the Settings app.
2. Tap your name.
3. Tap Payment & Shipping. You might be asked to sign in with your Apple ID.

• • To add a payment method, tap Add Payment Method.
  • To update a payment method, tap the payment method, then edit your information. You might need to enter the security code that's printed on your credit or debit card. If you see Apple Pay after the last 4 digits of the card number, go to the Wallet app to edit the card information.
  • To remove a payment method, tap Edit, then tap the Delete button.
  • To change the order of your payment methods, tap Edit, then use the move order icon .*

*Apple will attempt to charge payment methods in order from top to bottom. You can't change the order in which Apple ID balance is charged.

How to change your payment method on your Mac

1. Open the App Store on your Mac.
2. Click your name or the sign in button  at the bottom of the sidebar.
3. Click View Information.
4. Next to Payment Information, click Manage Payments. (If you're using an older version of macOS, click Edit to the right of Payment Type.) You might be asked to sign in with your Apple ID.
5. From here, you can do these things:

• • Update a payment method—Click Edit next to the payment method. You might need to enter the security code that's printed on your credit or debit card.
  • Add a payment method—Click Add Payment.
  • Remove a payment method—Click Edit next to the payment method, then click Remove.
  • Change the order of your payment methods—Hover your pointer over a payment method, then use the move order icon . Apple will attempt to charge payment methods in order from top to bottom. You can't change the order in which Apple ID balance is charged.

If you don't have an Apple device

To change your Apple ID payment method, use iTunes on your PC or follow the steps for your non-Apple device.

If you can't edit your payment information

Try updating to the latest version of iOS or iPadOS or macOS.

If you have subscriptions, have an unpaid balance, or share purchases with your Family Sharing group, you can't remove all payment information. Get help if you want to use no payment method with your Apple ID.

Manage payment methods that family members use

When you set up Family Sharing and turn on purchase sharing, one adult in the family — the family organizer — controls a single shared payment method for everyone in the family group.

If you're the family organizer, you can add multiple payment methods to your own Apple ID, but your family members can use only the first payment method in the list. If a family member can't make a purchase, the family organizer can move a different payment method to the top of the list.

Get help with other billing issues

• Identify unfamiliar charges.
• Request a refund.
• Cancel a subscription.

Ok since you got a new card... Question is....is the card number the same, but has different expiration and CCV?

IF so you will need to just go to settings > name > payment and shipping and tap on the existing card number and just update the cvv and expiration date and tap done top right. https://support.apple.com/en-us/HT201266

You. may also need to review your purchase history to see if you have any pending charges. This can result in your card being declined either because of insufficient funds to cover an unpaid order or your bank declines the transaction.

https://support.apple.com/en-us/HT204088

https://support.apple.com/en-us/HT203005

Also you could try updating you payment method on appleid.apple.com.

If your in a family sharing group and someone is sharing purchases, you will not be able to update your payment method until they turn off purchase sharing. https://support.apple.com/en-us/HT201079

Hope this helps ;)