How to modify my template

Hi there,

As showing below steps, I know how to create my template, but how can I modify it? It is not reasonable to go to each page to edit it.

1. Design your layout.
2. Select “Save current page as a Template” from “Templates” menu.
3. Enter template name.
4. Next, open (or create new) page where you want to place that template.
5. Select your template from the “Templates” menu.
6. It will be appended to the current page.

How to modify this template?