JavaScript is giving different values under one variable

Question

I'm creating a loading screen that will load when a user is connecting to the game that will be constantly playing YouTube videos using the iFrame API that will be fetched from a file named callback.php. Everything seems to work fine for the first song, except that after the first song it gets replayed and the track information above the video shows information for the next song...

I'm not a person who uses JavaScript regularly, and I've been forced to use it this time. I need to make sure that the whole system is getting the right values all of the time otherwise it will be unreliable and will cause problems.

My JavaScript code:

function youtubeDisable() {
    $('.youtube').addClass('youtube-novideo').removeClass('youtube');
    $("#youtube-widget").addClass('info').removeAttr('id');
    $(".youtube-novideo>.youtube-header>div:nth-child(2)>h1").html('Loading screen Playlists...');
    $(".youtube-novideo>.youtube-header>div:nth-child(2)>h2").remove();
    $(".youtube-novideo>.info").append("<p>Visit portal.repeatgaming.com to create Loading screen playlists.</p>");
    $("#youtube-preloader").remove();
    $(".youtube-novideo").show();
}

var song,
    playing,
    player,
    run=false,
    systemglitch=false;

var jqxhr = $.ajax("callback.php?action=doesuserhavemusic&steamid="+params.steamid).done(function(e) {
    if (e.success == true) {
        run = true;
        console.log('[PLAYLISTS] User '+params.steamid+' is subscribed to playlists and has songs within them.');
        var tag = document.createElement('script');
        tag.src = "https://www.youtube.com/iframe_api";
        var firstScriptTag = document.getElementsByTagName('script')[0];
        firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);
    } else {
        run = false;
        console.log('[PLAYLISTS] User '+params.steamid+' is not subscribed to any playlists. Not playing any music.');
        youtubeDisable();
    }
}).fail(function() {
    console.log('[PLAYLISTS] Failed to initialise. Assuming error with callback.');
    run = false;
    youtubeDisable();
    systemglitch = 'Failed to connect to Portal to fetch songs.';
});

function getNextSong(last_song) {
    last_song = last_song || false;

    if (last_song == false) {
        var jqxhr = $.ajax("callback.php?action=fetchnextsong&steamid="+params.steamid).done(function(e) {
            if (e.success == true) {
                console.log('[PLAYLISTS] Selecting song: '+e.songid);
                song = e.songid;
                return e.songid;
            } else {
                console.log('[PLAYLISTS] Failed to fetch next song: getNextSong()');
                run = false;
                systemglitch = 'Failed to connect to Portal to fetch songs.';
            }
        }).fail(function() {
            console.log('[PLAYLISTS] Failed to fetch next song: getNextSong()');
            run = false;
            systemglitch = 'Failed to connect to Portal to fetch songs.';
        });
    } else {
        var jqxhr = $.ajax("callback.php?action=fetchnextsong&steamid="+params.steamid+"&lastsong="+last_song).done(function(e) {
            if (e.success == true) {
                console.log('[PLAYLISTS] Selecting song (with last_song defined): '+e.songid);
                song = e.songid;
                return e.songid;
            } else {
                console.log('[PLAYLISTS] Failed to fetch next song (with last_song defined): getNextSong('+last_song+')');
                run = false;
                systemglitch = 'Failed to connect to Portal to fetch songs.';
            }
        }).fail(function() {
            console.log('[PLAYLISTS] Failed to fetch next song (with last_song defined): getNextSong('+last_song+')');
            run = false;
            systemglitch = 'Failed to connect to Portal to fetch songs.';
        });
    }
}

getNextSong();

function youtubeStart() {
    player = new YT.Player('youtube-widget', {
        height: '225',
        width: '400',
        controls: 0,
        events: {
            'onReady': youtubePlayerReady,
            'onStateChange': youtubePlayerStateChange,
            'onError': youtubePlayerError
        },
        playerVars: {
            'controls': 0,
            'showinfo': 0,
            'iv_load_policy': 3
        },
    });

    $(".youtube").show();
    $("#youtube-preloader").show();
}

function getSongInformation(songid, autogen) {
    autogen = autogen || true;

    var jqxhr = $.ajax("callback.php?action=fetchsonginformation&songid="+songid).done(function(e) {
        if (e.success == true) {
            if (autogen) {
                $(".youtube>.youtube-header>div:nth-child(2)>h1").text(e.snippet.title);
                $(".youtube>.youtube-header>div:nth-child(2)>h2").text(e.snippet.channelTitle);
            }

            return e;
        } else {
            console.log('[PLAYLISTS] Failed to fetch song information: getSongInformation('+songid+', '+autogen+')');
            run = false;
            systemglitch = 'Failed to connect to Portal to fetch songs.';
        }
    }).fail(function() {
        console.log('[PLAYLISTS] Failed to fetch song information: getSongInformation('+songid+', '+autogen+')');
        run = false;
        systemglitch = 'Failed to connect to Portal to fetch songs.';
    });
}

function youtubePlayerReady(event) {
    event.target.loadVideoById(song);
    player.setVolume(20);
}

function youtubePlayerStateChange(event) {
    switch (event.data) {
        case -1:
            break;
        case YT.PlayerState.ENDED:
            $("#youtube-preloader").show();
            youtubeLoadNewSong();
            break;
        case YT.PlayerState.PLAYING:
            $("#youtube-preloader").hide();
            getSongInformation(song, true);
            break;
        case YT.PlayerState.PAUSED:
            $("#youtube-preloader").show();
            player.playVideo();
            player.setVolume(20);
            break;
        case YT.PlayerState.BUFFERING:
            $("#youtube-preloader").show();
            break;
        case YT.PlayerState.CUED:
            break;
        default:
            break;
    }
}

function youtubeLoadNewSong() {
    getNextSong(song);
    player.loadVideoById(song);
    getSongInformation(song, true);
}

function youtubePlayerError(error) {
    console.log('[PLAYLISTS] Error: '+error.data);
}

function onYouTubeIframeAPIReady() {
    youtubeStart();
}

if (systemglitch != false) {
    console.log('[PLAYLISTS] System glitch: '+systemglitch);
}

Quick overview of the above file, just for TL;DR's sake:

1. Player checks if the player is subscribed to any playlists that contain songs.
2. Then the file gets the next song to play.
3. Set up the YouTube iFrame.
4. Start playing the preselected song.
5. Checks for when the video is finished and then calls the youtubeLoadNewSong() function to change songs
6. Video doesn't change (on first change) and the song information headers show the next videos information.

I'm using jQuery as you could probably tell. This issue is really making me annoyed, and I don't see why it isn't working. If I had code similar to this in PHP (my favourite language) it would work just fine, this is probably why I'm confused.

I'm sure the answer will be really simple *facepalms*, but I would really appreciate your help.

P.S: Sorry for the massive file...