I am starting a neuromuscular retraining program. The aim is the strengthen then lower scapula stabilizers (lower traps, sub scap, serratus anterior) while switching of the upper over active stabilizers ( upper traps, levator scap, rhomboid minor and major)

When the upper stabilizers get over developed they over power the lower ones causing the scapula to gradually float upwards, or off to the side into the arm pit. Also tight muscles in the anterior contribute to this.

Unfortunately you cant strengthen theses areas with out the supervision of a qualified PT, i mean you can try but i can gaurentee you are just going to use those over active muscles upper muscles as you have been for years.