Just wandering, in one of the episodes, tristans voice changes and then comes back in the next epdisode. I know LK does all the voices so why is it that he has to change the voice? Is it because in a real episode, the voice of tristan changes and then comes back?

The voice, in the original 4kids dub, did change from the Barney-esque voice to the more human-like voice, but it stuck that way. LittleKuriboh probably returned it back to the Barney voice because it made the character easier to parody, as it adds that childlike nature which only works with Barney voiced Tristan.

it changed back so he could do all the jokes about his voice changing
the death of his voice
the monster reborn of his voice
joey saying that hes been like a new person

lol it was sad when his voice changed

but it was soo funny!

Y: i use reborn the monster (still monster reborn) to resurrect tristan's original voice
T: hey, but i liked my new voice <img src='/images/emoticons/smiley4.png'>
Y: sorry tristan, its just easier to make fun of ou this way!
<img src='/images/emoticons/smiley2.png'> <img src='/images/emoticons/smiley2.png'> <img src='/images/emoticons/smiley2.png'>

lol i think he did it to be funny <img src='/images/emoticons/smiley1.png'>
a tristan with a barny based voice, lol, alot of puns and jokes could be made from that <img src='/images/emoticons/smiley7.png'>

Actually, I read from somewhere (the Abridged wiki, I think) that in the 4Kids dub, Tristan's dub was actually changed to a different actor at some point in the series. So the "death of Tristan's Voice" was kind of a knock off on that, I believe. But it was hilarious no less. Especially the RECONSTRUCTION:

"Tristan's Voice, have you been drinking?!"
"I can't remember, because I am sooo drunk!"
"Hey wait, don't run with those scissors!"
"You're not the boss of me!" *Trip.* "Ouch!"
"Oh no, he's dead."

Honestly, Tristan's old voice reminded me of a surfer with a head cold. LittleKuriboh's rendition makes him sound like Bullwinkle.