Any Advice wil be helpful

My 9 year old son is autistic and has quite a sheltered life.  He attended a small school and has a lot of friends however i have found that some to be easily inflicting him to say things and do things. 

his father and i have tired to explain that he does not need to tell everyone every conversation we have whether good or bad and that he should not believe his friends all the time but he is not taking it in and just says sorry even though he is not being told off.

Any advice on how i can make him understand that some children are taking advantage and not to do and believe everything they say. 

thanks in advance 

L