Change Xbox live to my current Gamertag

On 360 when I go online to my account, it has my old gamertag with the old pic, how do u switch it to the current tag, have a new computer, win 8.1, don't like it having a rough time with it, and it stiil has the old e-mail address for my Xbox live account
p.o. Dave

:)

 

Xbox gamertag transfer help

To be a bit more specific how do i make my current gamertag an xbox live gamertag?

Note: I have an account on the xbox one but want to carry over my gamertag from the 360 to the one.

 

gamertag XXX is no longer allowed

I ended up downloading my old profiles, but it wants me to pay 800 points to change that name. According to xbox policies I should be able to change my xbox gamertag once free of charge - "If you created your gamertag when you signed up for Xbox LIVE, you
can change your gamertag once for free." support.xbox.com/.../change-xbox-live-gamertag

Is there something preventing this name change for free, and will the old gamertag definitely be free'd up once I change it so I can change my current name "FUBAR PhD" to tptass?

 

The one showing on this forum at the moment violates the code of conduct,you really don`t want that one.