The Problem:

Arabic, and generally right to left languages, subtitles appear flipped from left to right. (As viewed in the following screen)

I have encountered many posts suggesting to disable SSA/ASS Subtitles in SMPlayer (Preferences>Subtitles>Fonts and colors>Enable normal subtitles).
The solution works but deprives the user of controlling the subtitles' border, color, shadow, etc.

A more logical solution is to disable subtitle flipping MPlayer option. Here's how to do that:
1- Open SMPlayer Preferences
2- Select Advanced (from right menu)
3- Select Options for MPlayer
4- In the Options box paste
Note: the Hebrew part in the option above does NOT change with Arabic. So, just paste it as it is with any Right-to-Left language.
5- Make sure you click OK to exit the Preferences window

Final Result:

With border, shadow and color configured as desired from SSA/ASS Subtitles option in SMPlayer's preferences

Note to moderators: I've searched for a "How to" or "Tutorials" section but didn't find any. Please move the post to the correct section if there's one.