What would you like help with ? Are you sure that the emails (if that's what you mean by 'notifications') are genuine :
Phishing and similar emails : Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support
Genuine iTunes emails : Identifying legitimate emails from the iTunes Store - Apple Support
If you want to change your account's password you can do so via http://appleid.apple.com
After changing it : What to do after you change your Apple ID email address or password - Apple Support