Redmine

I'd like to create subtasks of other tasks. Reading all the documentation Redmine has to offer makes it sound like this is very possible, but I cannot figure out how to do it. I followed the instructions on the user guide and setting the parent task after clicking Issue, then Update, then More is simply missing. I also read this has to be a permission you allow, but I see nothing like this in permissions (and I am an administrator).

Is this feature only available as a plugin or what am I missing? Thanks for any help you can give!