If you want to change your payment method, you must update it on the platform that you used to subscribe originally (iOS or Android).

On iPhone:

1. Open your iPhone Settings

2. Tap Apple ID

3. Tap Payment & Shipping

4. Tap Add Payment Method or tap Edit to update your payment method

On Android:

1. Open the Google Play Store

2. Tap the Menu icon

3. Tap My Account

4. Tap Add Payment Method or Edit Payment Method