First change the TV language to Arabic so wordings can start appearing from right to left, using the following steps:
On the remote, click "Menu" button.
Click down till you reach "Setup" menu, click "Enter" (Button with box and input arrow in the remote) to enter this menu item.
Select "Language", and click "Arabic" or "العربية", you will recognize the setup menu is showing now from right not left.
Second while playing the movie, you need to select "Arabic" encoding, using the following steps:
After clicking "Media.P" button, select "Movie" or "الفيديو".
Navigate to select a movie you would like to play (I'm assuming you have already srt file with the same movie name but with .srt extension).
Play the movie, and click "Tools" button on remote.
Navigate down till you reach "Subtitle setting" or "اعداد الترجمة", and click "Enter" (Button with box and input arrow in the remote).
Navigate down to "Encoding" or "ترميز" , and click "Enter" (Button with box and input arrow in the remote).
Select "Arabic" or "العربية".