This is what the web site www.saudifreeads.com showing.\
Also i cant chage the arabic language to be the defult language\
from language mamanger ---- set defult language --- and submit\
it dont accept the change in the language mamanger.
The admin side set the default language when the user first time comes to your site and stays like that until the user select another language, then the system keeps the user language on his computer by cookies, therefore your admin setting is correct but your language as a user is saved by cookie, you can try another new computer and you will see it is working like that.
As for the image attached I donot know what's your problem, again and last you need to translate all categories in each language you created, the system will grab any language if you have not translated specific categories to avoid displaying empty categories names, delete all then create new categories and translate the categories in every language you have.