Gamertag Stats

Hi, firstly, I apologize if this has already been asked.
After a long break from Halo I purchased the CE anniversary edition, I’ve logged into Waypoint both on the Xbox and P.C, but because I’ve changed my Gamertag its not showing my stats. I have searched my previous GT and all my stats and info are there.
Does anyone know how I can get Waypoint to recognize its the same account, everything is the same as before, ie e-mail address etc except my GT.
Hope someone can help.

Make sure you are signed into the e-mail linked to your Xbox LIVE account first.

Then, keep playing Halo, it will eventually update, just takes a while for Waypoint to catch up!