When you day After Effects is writing Arabic "wrong", what do you mean? More details please. Screenshots would be very helpful.
So would knowing exactly what version number of AE you're using. Is it 13.6.1?
i have AE version 13.7.2
the issue is that when i writing in Arabic on after effects the letters goes from left to right. Also the letters are separate.
After Effects does not currently support right-to-left text. There are a few workarounds. The best one I know of is to use AE's text animation engine.
In your timeline twirl down the text properties.
Click on Animate>Scale
Unlink the values and set it to -100 on x
Then, in the layer's scale properties, unlink the values and set it to -100 on x
That will get you right-to-left text.
Alternatively, you could create your text in Photoshop or Illustrator and import it.
Also, you are several versions behind. You are missing the entire CC 2015.3 release (which is basically CC 2016) and you are missing the CC 2017 release. None of them will get you right-to-left text yet, but you are missing some new features and a lot of bug fixes.
If you would like to see After Effects introduce support for right-to-left text, file a feature request.