If you would like to move a task from one project to another, you can simply click the client or project name and use the dropdown box to select where you would like to move it.
If you have built a task with several sub-tasks and you will repeat this task again - either for the same project, or a new project/client - you can easily duplicate it.
Open the task details and click the 3 dots in the upper right corner and choose duplicate.
"Copy of" will be added to the title to allow you to differentiate. The project, client, assignee, due date, description, and tasks will be duplicated to your new task. Any of these can be edited by clicking on them. The status will be set to the earlier status in your workflow. Time worked, attachments, and the comment feed will not be copied from the previous task.
To assign the duplicated task to a new project or client, simply click it in the details and use the dropdown box to change it to the appropriate place.