Under the Phone section, tap the Verify link. Then, hit Change.
Enter your new phone number, and then click Save.
The verification code is normally sent to your mobile phone number either through text message or voice call. You'll need to have an active number on your account.
Here's how to update or change your payment details :
Sign in to QuickBooks Online as a primary admin.
Select Settings ⚙, then Account and settings.
Select Billing & Subscription.
Next to your payment method, select Edit ✎.
This will launch the Wallet list. From this view you can:
Edit the payment method used for QuickBooks Online billing (expiration date, billing address, account holder name)
Add a new payment to be used for QuickBooks Online billing
Switch QuickBooks Online billing to previously stored payment method
After saving your change, the payment method will be displayed on the Billing & Subscription page.
For additional reference, please check this article: