apple account payment option is not showing on my payment options but I have balance inside.

To verify your payment information:

👉 Sign in to your Apple ID account page and edit / update your Apple ID details.

https://appleid.apple.com

On the Sidebar click Payment methods -> then tap Payments Methods and tap Manage payment method.

Or -> Change, add or remove Apple ID payment methods

Change, add or remove Apple ID payment methods – Apple Support (UK)

-> Add first the new card, then remove the old one.

See also -> Payment methods you can use with your Apple ID

Payment methods you can use with your Apple ID – Apple Support (UK)

although mine has balance in it.

See -> Check your Apple ID balance

Check your Apple ID balance – Apple Support (UK)

-> If you have add funds to your Apple ID balance, it would take about 1 to 3 business days.

Your account balance doesn't show as a payment method, although charges will normally be deducted from the account balance before a payment method is charged. The account balance is shown in a different place. See the last link posted above.