Thanks for your help. It is the duties i am having issue with and i have already altered them abit. I can't alter them anymore since i had already applied for express entry before and showed cic this job(duties) but didn't claim any points for it. they might suspicious if i change it in my second application. Don't you think?
Please correct me.. Did you apply or did you just submit your profile before?
There is a difference between these two. Making a profile doesn't mean you've applied, instead it means you have just submitted your application into the pool.
You are unable to apply untill you're invited to do so with ITA (Invitation To apply).
In the former case with ITA, if you have already applied with same job duties then yes it would be a big deal if you alter these duties as CIC already have rejected application's details (if any) . However, if you do so then make sure that you've appended an LOE along with reference letter.
Whereas, In latter case without ITA, if you have made your profile with wrong NOC previously then you can update it anytime that's the reason why they've provided the update button. If you're still suspicious about it, then simply withdraw your existing profile and make a new one with relevant job duties and NOC.
Hope this clarifies your doubts.