Must you be logged in to customize the nav menu?

Howdy. Here is the deal. I have a site that is a wordpress/coldfusion combo. The majority is wordpress, but there is one area that is coldfusion. To get to the coldfusion area the user must login, so there is a ‘Login’ tab on the menu. Once they login in, the ‘Login’ tab changes to ‘My Account’ in the CF section. The issue is if they navigate away from the one coldfusion folder, back into the wordpress areas (about, contact, faq, etc), the ‘My Account’ tab disappears.

So I need to add some functionality into the word press nav menu that reads the login cookie and shows the ‘My Account’ tab. A little confusing I know, so here is a bit of a diagramy thing:

home page (WP) -> ‘Login’ tab shows
User logs in
video page (CF) -> ‘Login’ tab now says ‘My Account’
User goes to any other page, say ‘About Us’
About us page is WP -> ‘My Account’ tab is gone!

I know how I would code this if this were a regular html/php site, but I am new to WP and after searching through the site files for an hour, I couldn’t even find the file with the WP nav menu code. From the study I have done, I guess all that stuff is in a DB somewhere? So do I need to actually log in to WP and code it in there?

Any hints, tips, or a good tutorial would be great, thanks you.