Thanks so much for the response!

Under Design I've selected the recommended template (Modern). Under Customization there is no option other than customizing fields. There you click manage. Then I get this message:

Custom fields aren't available in Simple Start. Upgrade your Quickbooks Online plan to create custom fields.

If I backup and choose any other template under Design, clicking Manage there takes me back to the old invoice template design center. That's great......if this is still going to be available after Oct. 16th? The emails I keep getting seem to suggest otherwise. 

Thanks so much.