The parents are always playing the significant roles in
children grow upthe growth of their children .
What Pahan has suggested is the best way to express this idea.
Not all the parents know what is their children really needsNot all parents know what their children really need
child needs / children need
Not all the parents know what is their children really needs, or they may have no time to teach or play with their children instead of bought TV or PC game to their children to keep them stay at home safely and quietly.
This sentence is too lengthy as well as crowded with so many ideas. Don't write long sentences. Keep them short - one sentence for one idea. You need to pay lots of attention to grammar and vocabulary. So, the best way for you to get a good start is writing shorter sentences.