To improve your metrics you may need to strengthen or stretch some of the muscles involved in performing the desired form. This is why Lumo Run gives you exercises at the end of your runs.
You also may need to teach your brain to use these muscles while you are running. This is why Lumo Run gives you in-run audio cues. Changing your form takes time as you need to strengthen muscles and/or retrain your body to move in a new way.
Listen to your body and build up slowly so you give your body time to adjust to the new demands.