Access your Account Management Menu

Click the Profile icon in upper right corner and select Account.  

Click Subscriptions from the left side menu.  

Click the Manage button under Active subscriptions to change and edit your current subscription choices (see options below)

Choose Add-Ons

Scroll down to the Add-on section and make your selection.

You can choose to Add Service or Remove Service.

You can Switch Term between monthly and annual using the toggle button for each subscription

After you've made your subscription choices, click Confirm, go to Checkout

At Checkout, Add or Update your payment method

You can click Pay Now to finalize your subscription choices.  Your browser will refresh and your subscriptions will become active immediately.