How do I change charge card for iCloud account

See this article about updating payment methods on various platforms: If you need to change or update your Apple ID payment method - Apple Support

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

Read the support article to which I provided a link. I can't be more specific because you have not told us what equipment you are using.

This will change your payment method used for any App or iTunes Store purchase. You cannot select one specifically for iCloud alone.