How can I add new card to the payment method in Apple Account

Card for what? The spa? I'll guess:

See this article for information about updating payment methods on various platforms (iPhone, Mac, etc.): If you need to change or update your Apple Account payment method - Apple Support

Here is how you update your payment method on an iPhone or iPad:

1. Open the Settings app.

2. Tap your name.

3. Tap Payment & Shipping (formerly Media & Purchases). You might be asked to sign in with your Apple ID.

4. Tap Add Payment Method, enter the new payment method, then tap Done.

5. Tap Edit.

6. Tap the red delete button next to the old payment method, then tap Delete.

Also note:

1) ”If you change your address, the credit or debit card information that you use with your Apple Account might be automatically updated by your financial institution, and you don't need to take action.”

2) “If there's an issue [such as you having a subscription or being a Family Sharing Organizer], add a new card first, then remove the old card."

If an app or feature on your device is not working, not appearing, or is restricted (grayed out), it may have been disabled using Screen Time, or by an IT administrator if you are using a device owned by an employer or educational institution.

- Read this support article If your Apple ID or other options are greyed out in Settings —> If your Apple Account is grayed out in Settings - Apple Support

Tap Settings > Screen Time > Content & Privacy > scroll to Allow Changes and turn on.

- If the device is managed (Settings > General > VPN & Device Management), contact the IT department that is doing the managing.

You might want to start by checking your region: ▷ Open Settings ➢ General ➢ Language & Region ➢ Region.

Now, here’s the fully detailed procedure to adding a card:⇣

Try the following:

• Be sure to activate your card before attempting to add it to Apple Wallet.
• Be sure card has not expired.
• Be sure to verify all information on the card matches exactly.

—Apple Pay Support—

• Set up Apple Pay.
• Pay Participating Banks.
• Can’t add a card to Apple Wallet.

If none of those work, then try linking the payment method:

Open Settings ➢ your name at the top of the list ➢ Payment & Shipping ➢ Add Payment Method.

Once the payment method has been added, you should have the option to link it to Apple Pay.

Need more help?

• Contact Support.
• Payment Method Declined.

Good luck! 👋🏼😉