Question

Properties changed in the duplicated subtasks also change in the original task, like they were connected, not just copied and existing as individual, new rows in the database. Same happens while using a template -> even if in the tamplate the propery e.g. date is left blank, when I use the template and create new row in the database and fill in some data (e.g. dates of subtasks), they also change in the template itself. I'd like to use a blank template (or a duplicate) and fill in the data separately for individual subtasks, not changing anything in the originally duplicated task or in the template.
How do I do that?

Answer 1

Use the templates inside the database clicking in the "New" button little down arrow and choose "New template".

That will create new items based on your template as you need.