I am unable to select my money

Hey there,

You can use your Apple Account balance to buy apps, pay for subscriptions, and more. But for some purchases, Apple Account balance can't be used. Learn what you can buy with your Apple Account balance.

Also you have to know that the Apple Account balance isn’t available in all countries or regions. See if you can pay with Apple Account balance in your country or region.

How can I select my apple ID money?

if you want to use your Apple Account balance, you need to set your Apple Account balance as your default payment.

See -> Add a payment method to your Apple ID

Add a payment method to your Apple ID – Apple Support (UK)

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Add a payment method on your iPhone or iPad

1. Open the Settings app.
2. Tap your name.
3. Tap Media & Purchases, then tap View Account. You may be asked to sign in with your Apple ID.
4. Tap Manage Payments.
5. Tap Add Payment Method.

 6. Enter the payment method details, then tap Done.

When you buy something in the App Store or iTunes Store the first thing that is used is Apple ID Balance.