This is why your Overhead Squat sucks
The Overhead Squat is one of the, if not the most challenging position newbies to Olympic Weightlifting are faced with. Very rarely I see beginners who can naturally go into this position from the beginning. More likely are big flaws in the squat: Coming of the ground with the heels, leaning the torso forward, loosing the bar to the front.
No other squat variation requires more mobility, body awareness, balance and stability. Don´t panic if it takes you a while to get there and you feel super uncomfortable "in the whole" - how often have you been squatting with a long object over your head before? See! It takes time but one day, the Overhead position will feel just logical. But first, you have to assess which of the many possible reasons are holding you back. Here comes an overview.
Thoracic Spine mobility
A rounded upper back is the strongest sign for a limited mobility of the thoracic spine. The issue often is caused by spending a lot of time in a position with the arms forward, e.g. typing on the keyboard or while driving the car.
A reduced thoracic spine mobility often leads to loosing the bar in front since the arms can not go far enough behind to secure it directly overhead. Working on a better flexion and rotation of the mid back is key. My favorite one is the fascia relieve with a Peanut:
A nice one for the rotation without any equipment required:
Especially if you have a gym background and did a lot of bench and other forward presses, your pecs might be overly developed and tight which again pulls the shoulder to the front, causing the bar to travel to much towards the forehead.
The first step to solve that problem is lesser chest muscle training (for a reason Weightlifter and CrossFitter hardly bench) and/or at least the same volume of balancing exercises such as rowing movements (Bend over Row, T-Bar row etc.).
Directly before an Overhead Squat or Squat Snatch session, take time to stretch out your pecs. This might be the most basic one:
A good internal and external rotation of the shoulder is key to get a good transition from the pull to the receiving position and finally to manage a strong catch overhead.
This is the most basic test to assess your rotation abilities:
If you fail the test (= large distance between both hands), work on exactly this also called "Archer Stretch" or "Apley´s Scratch", use a band between the hands if needed and stay at least 30 sec in this pose.
It is very normal for one shoulder being much more mobile in the internal rotation than the other one. Put more effort in the stiffer side to correct imbalances.
A tight ankle will cause problems in every squat variation. Also and especially in the Overhead Squat, it will limit the torso to sit upright in the receiving position - when the shins can´t go into a inclined position, the upper body will compensate by leaning forward - this means much torque on knees and lower back and a suboptimal overhead hold of the weight.
It also often causes the heels coming off the ground which leads to a shift of the load from the mid-food (where it should be during a squat) to the toes - a very instable posture.
If the knee can´t go anywhere close to the toes, it could be caused by the calves, Achilles tendon or the ankle joint itself. A good yoga exercise to stretch all of them at the same time is the Low Dragon:
Claves and Achilles tendon can be rolled out with a foam roller, lacross ball or the like:
General lack of strength and stability
If struggles with the Overhead Squat are not caused by joint restrictions or muscle tightness, a general weakness overhead can be the cause as well.
Often it already helps to focus on locking the elbows out once the bar has been received - very often people get passive in the squat and let the arms bend, which is a very weak and hard to stabilize position.
General strength overhead can be build with behind the neck presses that closely mimic the Overhead Squat:
Or even better than the standing version: The Sotts Press (your weight might be insignificant lower than what Klokov uses):
There are numerous exercises for improved shoulder mobility. This is my favorite: