You must first create an Account. Follow instructions for how to create account above.
Once logged in, select Subscriptions.
Select your active subscription number.
Then select "Edit".
Next to the product you'd like to swap out, click the edit icon to the right.
Next, expand the item you'd like to replace it with and press the "Select Product" button.
Lastly, check the "I understand" statement box and submit with the "Confirm" button.