Hi Abdullah,
Thanks for posting back and sharing.
I double check the screenshots you shared in original reply, it seems the issue is that although the content is aligned to the right, but the words are displayed from left to right.
May I confirm if you have followed Doug's suggestion above to set Right to Left direction?
As you mentioned new documents you create don't have the issue, you may try to copy content from the affected documents to new documents you create and check the result.
In addition, try to open those documents via Word Online as a workaround.
This is what the sample document you shared looks like when I open it in Current Channel, Version 2010 (Build 13628.20448) of Word from my side.

Honestly since I'm not familiar with Arabic language, I cannot identify if the issue happens or not. Really sorry about it.
To better help you do troubleshooting, would you mind if we help you move this thread to Arabic category? The engineers will be more familiar with Arabic and better assist you further.
Really sorry for the inconvenience. We appreciate your understanding.
Best Regards,
Tina