It hasn't "changed" in the sense that I've lost attraction to one gender or solely find myself attracted to another, but I experience fluctuation in attraction - finding women more appealing sometimes, men others.
Mine has a bit, but barely. In highschool I identified as bi because i liked girls and was scared to admit it. Then when I dated girls I called myself a lesbian. Then in college I met this great guy and we've been together ever since, but I still feel far more attracted to women than men. I just stick with Bi or Pan now for convenience.
Mine has changed overtime. I was straight for like almost my whole life but I started noticing girls around 2014 and I thought I was bi but I realized I was wrong as I was also attracted to people of other genders. I figured out I was pan after a while and started identifying with pan ever since.
