Your pup has been on the planet four months. How is she supposed to "Know" all of this stuff you think she knows? Your pup is looking for leadership and now's the time to bring that on! Dogs operate "Nose, then eyes, then ears". All that shouting and smacking is just teaching to be afraid when you go berserk. She's not learning anything.
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Davidh is right. Patience and consistency is key. Try to use as little sound as possible. Practice leadership. Different dogs need different amounts of exercise. It's starting to cool off. Alter your schedule to walk her when she needs it and bump it up to two sessions a day and see if that helps.
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elearn - I love what you said! Using the clicker (little sound) - and treats (
nose eyes ears!) you are redirecting your pup's energy toward a leadership exercise. Your pup hears the clicker and instantly knows something good is coming (because that's what a clicker does) and then she has an opportunity to please you and get a food reward. What could be better for a pup learning the behavior you desire from her/him? Fabulous!