First, if the problem of high and low shoulders is too serious, it can only be solved through correction. In adolescence, you can effectively keep your standing posture level with your shoulders by wearing tools similar to those that were very popular before. Keep wearing these corrective tools for a period of time, and you will find that the curvature of your spine has improved significantly. If it is slightly high and low shoulders, you can do some training, such as lifting dumbbells (with appropriate weight) on the low shoulders and doing forward lifting.
Second, the solution to the round shoulder is to exercise muscle groups, mainly the underdeveloped chest muscles, and the curvature of the spine leads to round shoulders, which can be used for forehand rowing, neck pull-down and so on.
Third, the most important thing is the usual prevention, improving the correct sitting posture, learning good reading habits and strengthening exercise in life can effectively prevent such problems.