Golfers hit behind the ball for a few reasons. But the main cause is the low point in the swing happens to early.
One drill that will give you great feedback is scratch a line in the ground with a tee. Start with the clubhead on the line and make small swings and hit at the line or on the target side of the line. Next, have a ball ready on the line beside your practice swings and move and hit the ball. Try to recreate the “feel” of hitting at the line or in front. Hit 20 balls. check the results. Take a picture.
Next time do the same drill and hit 20 balls. Take a picture.
Compare the before and after. If the divots are closer to the line or toward the target, then you are making progress.