You should stop applying. Anyone who applies "various times" in only 2 years is likely to be denied, because they have applied too many times.
What it means is that when you applied, you left blank something that you should have filled. However, doing it now won't necessarily help, because you've already applied so much.
The first and most important step is to build a longer record of not applying, not even once, for over a year. After you have done that, then apply only one time, being very, very careful to fill in every blank space, and leave nothing blank, and then stop applying, immediately, without applying even one more time until after waiting over a year.