Once you create a task list by either saving an existing task list as a template or creating a task list template from scratch, you can edit the template at any time.
1. Go to a workspace and select Options > Manage Task List Templates.
2a. In a task list template that you wish to edit, click on Add new task for this template to add more tasks.
2b. You can also edit existing tasks by clicking on the down arrow next to the task and selecting Edit. You can do things like add subtasks and update the description, update the due date and more. Once you are done making changes, be sure to hit the Update button.