Studio Glitch Help with Music and Sound Audios?

Random numbers are generated using a seed. By changing this seed, you can change the numbers generated. In order to change it, you'll need math.randomseed:

print('ran')
local musicholder = script.Parent
math.randomseed(tick());

local songList = {
    musicholder:WaitForChild('CW'),
    musicholder:WaitForChild('DeckDubstep'),
    musicholder:WaitForChild('EhDe'),
    musicholder:WaitForChild('JayKode'),
    musicholder:WaitForChild('Ookay'),
    musicholder:WaitForChild('SantaComes'),
    musicholder:WaitForChild('XmasToMe'),
    --musicholder:WaitForChild('Song'),
    --musicholder:WaitForChild('Song'),
    --musicholder:WaitForChild('Song')
    -- we wait for each song
    -- add the rest of the songs to this list
}
local songCount = #songList -- this returns the number of items in the table above so we only change as little code as possible when adding songs

while true do
    wait(3)
    local songNum = math.random(1, songCount) -- gets a random number in the range of the number of songs
    print(songNum)
    songList[songNum]:Play() -- we access the sound in the table and play it
    songList[songNum].Ended:Wait() -- we wait until the song has finished then play anther song
end

We use tick because tick is a function which returns the amount of time since the UNIX epoch. Since time is always changing, we can be sure that it will be a different number each time the game runs.

As an added measure, you can make sure you're choosing a different song than the song that just played easily:

print('ran')
local musicholder = script.Parent
math.randomseed(tick());

local songList = {
    musicholder:WaitForChild('CW'),
    musicholder:WaitForChild('DeckDubstep'),
    musicholder:WaitForChild('EhDe'),
    musicholder:WaitForChild('JayKode'),
    musicholder:WaitForChild('Ookay'),
    musicholder:WaitForChild('SantaComes'),
    musicholder:WaitForChild('XmasToMe'),
    --musicholder:WaitForChild('Song'),
    --musicholder:WaitForChild('Song'),
    --musicholder:WaitForChild('Song')
    -- we wait for each song
    -- add the rest of the songs to this list
}
local songCount = #songList -- this returns the number of items in the table above so we only change as little code as possible when adding songs
local played = {}; --// Create a table for played songs.

while true do
    wait(3)
    local songNum = math.random(1, songCount) -- gets a random number in the range of the number of songs

    if played[songNum] then --// Check if the song has been played.
        repeat songNum = math.random(songCount) until not played[songNum];
        --// Choose a new song.
    end;
    played[songNum] = true; --// Record that this song has been played.
    if #played == songCount then
        played = {}; --// If all of them have been played, reset the table.
    end;

    print(songNum)
    songList[songNum]:Play() -- we access the sound in the table and play it
    songList[songNum].Ended:Wait() -- we wait until the song has finished then play anther song
end

Hope this helped.

PS: I did it for you this time, but in the future please be sure to properly indent your code; this makes it easier to read for anyone trying to help you out.

You could've just read this xD link

math.randomseed(tick())
print('ran')
local musicholder = script.Parent

local songList = {
musicholder:WaitForChild('CW'),
musicholder:WaitForChild('DeckDubstep'),
musicholder:WaitForChild('EhDe'),
musicholder:WaitForChild('JayKode'),
musicholder:WaitForChild('Ookay'),
musicholder:WaitForChild('SantaComes'),
musicholder:WaitForChild('XmasToMe'),
--musicholder:WaitForChild('Song'),
--musicholder:WaitForChild('Song'),
--musicholder:WaitForChild('Song')
-- we wait for each song
-- add the rest of the songs to this list
}
local songCount = #songList -- this returns the number of items in the table above so we only change as little code as possible when adding songs

while true do
wait(3)
local songNum = math.random(1, songCount) -- gets a random number in the range of the number of songs
print(songNum)
songList[songNum]:Play() -- we access the sound in the table and play it
songList[songNum].Ended:Wait() -- we wait until the song has finished then play anther song
end

In game, open the developer console and see which value songNum is being printed. If it is the same one, try math.randomseed()