From INSIDE THE SUBSCRIPTIONS PORTAL, click the "Payment Methods" tab (yellow arrow below).Click the "Add payment method" button (pink arrow below).Fill in all the relevant fields.If you want to switch all your subscriptions to the new payment method, leave the box next to "Update all of my subscriptions to use this payment method" checked and click "Add payment method".If you only want some of your subscriptions to use the new payment method, uncheck the box next to "Update all of my subscriptions to use this payment method" and click "Add payment method".Un-click any subscriptions which you do NOT want to use the new credit card (purple arrows below), then click the "Move subscriptions" button (black arrow below).If you don't want to assign any subscriptions to the new card right now, click "Skip for now" (green arrow below).