iOS
- Open the Settings app on your device.
- Tap on your name at the top of the screen.
- Tap Payment & Shipping (Here you may be asked to sign in with your Apple-ID)
- Tap your current payment method and edit your information. (Here you may be asked to enter the security code on your credit/debit card)
If you have multiple payment methods Apple will try to charge them in order from the top. To change the order of your payment methods press edit and use the move order icon to move the methods.
Android
- Open the Google Play app on your device.
- Tap on your profile icon at the top right of the screen.
- Tap Payments & subscriptions.
- Tap Subscriptions.
- Select the subscription you want to change.
- Tap Manage
- Tap Update
- Follow the instructions on the screen to update your payment method.
If your payment method has insufficient funds or is declined for another reason your subscription will be canceled. To avoid this you could add another payment method