Nothing in the 4S notes app to let you select one account or the other and syncing is on for all related emails. That's why I can't figure it out.Also check your email settings. I had notes off in all my email addresses and so I didn't see any of the notes in the app. I turned them on under each email address and then they showed up when you go to the notes app. At the top of the notes app there is an accounts tab and you can click on each account and see where they are stored. I thought I had to type them all out again, but checked my old iPhone and saw the account selection. I didn't realize they were linked to the email accounts.
I don't have that on my iPhone, my iPad has it, but nothing in the phone.Under Settings, Mail, Contacts, Cal and then under the email account there is an on/off slider for email and notes. I turned notes on for all my accounts and then go back to the Notes app and in the upper left there is an accounts button and it should should your email accounts that you can click on and my notes were under one of those accounts. Then I just turn notes off back under the settings for the other accounts that did not have notes associated with them.
I originally tried the syncing under the info tab in iTunes and didn't see the notes until I found the slider in the settings under the mail, contacts, cal.