If I change my home xbox, will the credit card saved will be on the other xbox?

no your friend will not have card info cause that is just only on your account.

Your friend would need access to your account in order to be able to do that, which they shouldn't have. The Home setting wouldn't allow them to use the card on your account.

Thank you very much! He will be so happy

Hey Adam

Thank you for taking the time to post this on the Xbox Forums. We understand that you are inquiring about the status of your payment instrument information from your account when configuring your account as the Home Xbox on another console.

As stated above by the other Xbox Forums Ambassadors, unless you someone else know your account information, or you have your account sign-in and security preferences configured a certain way, no one should be able to access your payment information, as
this is attached to your account and not the console.

As there is no further information that we can provide to you on this matter, we will now be locking this thread. If you have any other questions or concerns, please, feel free to create a new thread and we will cater to you there.

Thank you for being part of the Xbox Family and we wish you a wonderful day!

the credit card is linked to your account so he would need to be signed in to your account to make purchases.

if you are signing in to the Xbox and setting it as your Home then signing out, if he doesn't have your sign in info then he won't be able to make purchases.

you can also set a passkey on purchases

https://support.xbox.com/en-US/my-account/security/passkey-purchases

Your friend would need access to your account in order to be able to do that, which they shouldn't have. The Home setting wouldn't allow them to use the card on your account.