The front thigh can vary from person to person, but I think if there is a lack of muscle, there can be stimulation. However, as you progress in your workouts, it seems important that the stimulation becomes more focused on the back thigh. For beginners, it is a natural phenomenon that stimulation also goes to the coordinating muscles, not just the primary muscles.

The back thigh is getting stimulated, but the front thigh also hurts..

You need to stimulate the back of the thigh.