If your blogs have been migrated to Beta (Layout), then you'd have "Customize" in the Navbar above your Title or "Layout" instead of "Template" in your dashboard. Click on either and it'll offer to upgrade your template. If Customize and Layout aren't there, your blogs haven't been fully converted to Beta. If they are there, click on them so that you can Upgrade your template to Beta. You can also check beneath the Template tab for "Customize Design" and click on that to Upgrade your template.