If you already have a monthly plan and would like to switch to the annual plan, you can follow these steps:
Open your profile in the upper right corner of your account.
Select "Manage subscription."
A new page will open. Under Billing, select "Update plan."
Under "Plans Available" select either "Monthly" or "Yearly."
Select "Continue" and confirm the change.
If any additional payment is due, you will be charged when you confirm your new plan.