How to update my billing information in iCloud?

Here's what I received via email. Well, there's no where for me to find settings. And when I attempt to update my billing info on Mac or PC, there's only one option . . . to upgrade. I don't intend to upgrade. So this instruction list isn't useful for me to update my billing info. Thanks.

Follow the instructions below to update your billing information:

1.Go to Settings > [your name] > iTunes & App Store.

2.Tap your Apple ID, then tap View Apple ID. You might be asked to sign in.

3.Tap Manage Payments (if you’re using an older version of iOS, tap Payment Information) and follow the prompts.

You can also update your billing information on a Mac or PC.

[Re-Titled by Moderator]