Which of the following can't you do in the custom metrics window?

In the X Ads Manager, the custom metrics window is strictly a reporting and data visualization tool, which means you cannot add a new funding source within this specific interface. While the custom metrics window gives you the flexibility to add, delete, or rearrange data columns to better analyze your campaign's performance, it does not handle administrative or financial account settings. To update your payment methods or manage your budget's source of funds, you must navigate to the "Billing" or "Account Settings" section of the Ads Manager, as these sensitive financial configurations are kept separate from the day-to-day performance tracking tools.