Training pup. How to move to next command.

9 week old cockerspaniel.

Recently got my first pup and she's been great, slowly getting used to her crate at night and has already learn sit command.

I now want to move to getting her to stay or lie down, appreciate she's still young and may be expecting too much, however whenever I go into training mode with her, she knows and instantly goes and sits. I feel she is confused why no treat comes and is just on autopilot. My question is should the sitting still be rewarded with praise/treat, and how to you move on to the next command.

TIA.