I have asked this once before, and got no answer other then change me GT. But I think that my ? wasn't fully understood, or it just anoys me more than you think.
When other ppl see my GT it showes up SiNiStErSiN but on my screen on my Xbox it is as I have typed it, SinisterSin.
Now maby it can not be corrected, I don't know. But I don't fully understand why this has happened in the first place.