The seated row exercise is the best for improving your posture.
Steps To Do Seated Cable Row Exercise:
*Sit upright on the bench, facing the low pulley row machine with a V-bar.
*Keep your feet up on the front platform, making sure your knees are slightly bent but not locked.
*Lean over, keeping the natural alignment of your back, and grab the V-bar.
*Keep your arms extended and pull back your torso so that it is at a right angle with your legs. Keep your lower back slightly arched, chest out, and shoulders relaxed. This is the starting position.
*Keeping your torso stationary, pull the handles of the V-bar back. Breathe out, keep your arms close to your body, and pull the V-bar until your thumbs touch your abs. Squeeze your back muscles.
*Hold this pose for a second. Slowly release the contraction and go back to the starting position.