The GC web-page says this:
When you switch from a Quarterly to an Annual renewing Premium membership, you don’t lose any Premium membership time that you paid for.
Your new membership will start on the day the previous membership expires.
In your account settings, select Membership.
Select Edit Membership.
Select Stop Recurring Membership to cancel your current renewing Premium membership.
Purchase an annual membership.
But I cannot find these particular elements on my membership page. So how do I switch from Quarterly to Annual auto-renew?