Q&A for How to Change Google Play Payment Method

Your home address or whatever address is associated with your credit card.

Then obviously you would need to correct the errors/mistakes. The "billing address" is their last resort to send you the bill at that real address.

Go to the Google Play homepage and click your avatar. Go to settings > payment > you can change it there.

To change the payment options for in-app purchases on your Galaxy S21 Ultra from your son's account back to yours, switch Google accounts in the Google Play Store. Open the Google Play Store app, tap your profile picture in the top right corner, tap the down arrow next to your account name, and select your account. If needed, add your account and sign in. Once switched, your payment methods should update. Double-check by going to "Payments & subscriptions" > "Payment methods." If issues persist, ensure your Google account is the primary account, check for parental controls, and update the Google Play Store app if needed.

To reset your mobile carrier billing method on Google Play, open the Google Play Store app, go to "Payment methods" in your account settings, and add your carrier billing details again. Ensure your carrier supports Google Play billing and that you have a valid billing agreement with them.