用户登录后如何动态更新指令？

I have an app with a navbar directive and basic sign up/log in functionality. I want to change some of the words on the nav bar (from 'signup/login' to 'sign out') once the user is logged in, but I can't figure out the best (or even one) way to do this. I've tried setting the value of the variable/binding I want to change to a factory that gets updated when the user logs in, but this doesn't work, and the directive doesn't update with its new value.I have an app with a navbar directive and basic