Yonak
Early on, you've got to make sure she knows you are the alpha dog, without being cruel. Correct her sternly and show her love. You want her to obey you out of respect and because you're the boss and the leader, but not out of fear ; after all, what kind of companionship would that be ? Reprimanding her by whacking her with a rolled-up newspaper, coupled with a stern "no" while pointing to the chewed cord is effective, but also play with her and scratch her at other times.

Training a dog is an extremely frustrating exercise, but also very rewarding in the end. Unfortunately, it takes a long time with lots of chewed cords in the interim. It takes a commitment of your time and focus, as well as patience. You can't let her get away with things because if you let her test your limits she's challenging your alpha dog status. Good luck to you, and have fun.