Play Store:

  1. Open the Google Play app or  go to  play.google.com 
  2. At the top right, tap the profile icon.
  3. Select Payments and subscriptions > Payment methods.
  4. Select Add a payment method.

Tap Edit Payment Method to update your information. 

Official guide from Google

 

App Store:

  1. Open the Settings app.
  2. Tap your name.
  3. Tap Payment & Shipping. You might be asked to sign in with your Apple ID.
  4. Tap Add Payment Method.

To edit a payment method – tap the payment method, then edit your information and tap Done.

Official guide from Apple 

 
Amazon Appstore:
  1. In Your Account, select Your Payments.
  2. Do one of the following:
    • To add a payment method, select the Add a payment method link under the category that you want to add.
    • To edit or remove a payment method, select the card that you wish to edit on the left side of the page. The card opens in the center of the page. Click Edit under the card name. You can update your billing address, select a default card, update card details or remove the card from your account. Select Remove from wallet to remove the card from your account.
  3. Follow the on-screen instructions.

Official guide from Amazon