Could you add an option so that they are not grouped by stack or just change it so that they are not grouped by stack. It limits the usefulness of the sort parameters. If they weren't sorted by stack, I could still go into each stack and view them according to whatever parameters I choose. So as it stands, I suppose it would save me from having to change the parameters each time I moved to another stack. But I don't think this is more likely to be something I would be doing more than I would want to have all my notes grouped together according to some sort parameter (can't think of a time where I've needed the former.)

As of now, I can get around this, as you have seen, by creating a smart stack of notes where "appears in study sessions" is true. But it makes for some intensive processing where I have to bear with some pinwheeling. Perhaps that would not be the case if the default were to not sort All Notes by stack.