To change your SimpleSet subscription from monthly to annual, follow these instructions:

1.  Navigate to Settings on the top right.

2.  Select Billing.

3. Choose View Invoices /Update Billing.

You'll be taken to a new screen.  Follow these instructions:

1. Click on your current subscription

2. Choose Edit Subscription.

3. Choose Change.

4. There will only be one plan option, chose it .

5. You end up here - click update :) 

Done!