Billing Changes[ Edited ]
Thanks for reaching out.
Billing is set up at the child level. If you have Consolidated Billing, you can change the payment method in the Billing settings of the child account.
If you don't see the option to 'change who pays' in the account, I recommend getting in touch with the AdWords team. They will be able to look into your account and help identify the problem.
I would like to change companies name on the billings from the past, as I mixed a companies and one company paid for other's adwords. Can I somehow change companies name in all billings? It would be a headache for our accountant.