It is undoubtedly true that the majority of children in the modern world prefer watching television to engaging in outdoor activities. Although this arises because of several reasons, there are still some solutions for (correct: to) this negative trend.
There are some main causes of children’s bias towards watching television. One main reason is that as technological products have become cheaper these days, most families have one or more television (correct: one or more television sets) in their houses ("homes" is more frequently used in this case I think), which enable (you must use "enables" if what you want to say is the fact that most families have more television sets installed in their homes makes the children develop a TV watching routine and not that those television sets that make them do it) young children to watch television routinely. Another critical cause of children’s watching habit is that they lack care from their parents. Since society becomes (you should use "has become". Or if you wish to use "becomes", you ought to change "since" into "as") more and more competitive, people have to spend most of their time working rather than going home and playing (correct: go home and play) with their young children. This lack of care pushes children to use television as their main way of entertainment.
However, parents can encourage outdoor activities by taking proper actions (The phrase "take action" is a fixed phrase, so you cannot add an "s" to "action"). Firstly, this can be done by playing sports with children. For example, as young boys often enjoy playing football, at the weekend fathers should take them to the park and play football with them. If parents maintain this routinely (I would advise using maintain this routine as maintain sth routinely would sound a little redundant) , children will establish the habit to play sports regularly. Secondly, it is necessary to limit the time children watch television (limit (the amount of time children watch television)/(the children's watching time)). Parents should allow their children to watch TV for only one or two hours at the weekend (at/ on weekends). Finally, parents should explain to their children the harmfulness of watching television excessively and the benefits their children ( awkwardness can occur here so you'd better use "they"). Since their children can be wrongly interpreted as the children's children :D) can gain when they engage (alternatives: partake, take part) in outdoor activities/recreations/ pursuits/ diversions.
In conclusion, today children tend to watch television excessively (to avoid repetition, you can write "significantly more than their past counterparts") because of many (the above/ mentioned) reasons. However, if parents take prompt actions (correct: take prompt action. You could use take good/prompt steps/measures as well), they can still cope with this negative (you could use "worrying") trend (alternatives: pattern, tendency (I recommend using this word among others) or predisposition) among youngsters.
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Besides a few grammatical errors, this is an acceptable essay. I would give it a score between 6,5-7,5.
You should try not to repeat specific words severval times. This could give the examiner the impression that you do not have a strong command of vocabulary as shown by your inflexibility in employing words. Therefore, in addition to the corrections of the errors, I suggested alternatives to some words that you can use to widen the range of the vocabulary in your work.
Finally, I made some small corrections to make your writing more readable.
Hope you find it useful.
Good luck!