When you create new content, there is an option to select prefill from the initial window where you put in tytle, type, and initiatives. When you select a content type that has prefill options set up, a new Prefill field pops up with the prefill options. That does not happen when creating an idea.
Similarly, when creating content if you do not select prefills from the Create New Content pop up, you can 'Apply Prefills' from the content job itself, with a drop down by the submit & publish buttons. That drop-down would be helpful on ideas as well.