why does my script change the amount of money but it doesnt change the leaderboard amount?

BIG REQUEST ONLY FOR THOSE WHO HAVE A LOT OF TIME IN THEIR HANDS!

Leaaderboard Script:

print("Leaderboard script version 3.00 loaded")

--------------------------------------------------------------------------------------------------------------

function onXPChanged(player, XP, level)
    if XP.Value>=level.Value * 10 then -- Lv 1 to Lv 2 need 20 XP 
    XP.Value = 0
    level.Value = level.Value + 1 
    end
end

function onLevelUp(player, XP, level)
    local m = Instance.new("Hint")
    m.Parent = game.Workspace
    m.Text = player.Name .. " has leveled up!" -- the message display when player lv up
    wait(3)
    m.Parent = nil
   player.Humanoid.Health = 0
end


function onPlayerRespawned(player)
    wait(5)

    player.Character.Humanoid.Health = player.Character.Humanoid.Health + player.leaderstats.Level * 10

    player.Character.Humanoid.MaxHealth = player.Character.Humanoid.MaxHealth + player.leaderstats.Level * 10

end

function onPlayerEntered(newPlayer)

    _G.stats = Instance.new("IntValue")
    _G.stats.Name = "leaderstats"
    local stats2 = Instance.new("IntValue")
    stats2.Name = "Tycoon"


    _G.cash = Instance.new("IntValue")
    _G.cash.Name = "Tront Gems"                 --Change "Cash" to change the currency name.
    _G.cash.Value = 10          --Change the 0 to how much you want people to start with

   local kills = Instance.new("IntValue")
    kills.Name = "Player Kills"
    kills.Value = 0

    local deaths = Instance.new("IntValue")
    deaths.Name = "Deaths"
    deaths.Value = 0

   level = Instance.new("IntValue")
   level.Name = "Level" -- The Name of LV
   level.Value = 1

   xp = Instance.new("IntValue")
   xp.Name = "XP" -- The Name of XP
   xp.Value = 0

   _G.cash.Parent = _G.stats
    stats2.Parent = newPlayer   
    _G.stats.Parent = newPlayer
    kills.Parent = _G.stats
    deaths.Parent = _G.stats
   level.Parent = _G.stats
   xp.Parent = _G.stats

    xp.Changed:connect(function() onXPChanged(newPlayer, xp, level) end)
    level.Changed:connect(function() onLevelUp(newPlayer, xp, level) end)

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--[[repeat 
if game.Players.RealRexTerm.UserId == 350003413
    then 
    _G.cash.Value = 1000
    level.Value = 50
    kills.Value = 99999
    deaths.Value = -99999
elseif game.Players.RealRexTerm.UserId ~= 350003413
    then wait(1000)
    end
until game.Players.RealRexTerm.UserId == 350003413

repeat 
if game.Players.Myminimarshmallow.UserId == 197854508
    then 
    _G.cash.Value = 1000
    level.Value = 50
    kills.Value = 99999
    deaths.Value = -99999
elseif game.Players.Myminimarshmallow.UserId ~= 197854508
    then wait(1000)
    end
until game.Players.Myminimarshmallow.UserId == 197854508]]


---------------------------------------------------------------------------------------------------------------
-- Do not edit past here or you will be risking breaking the script!!!! --
---------------------------------------------------------------------------------------------------------------

    -- VERY UGLY HACK
    -- Will this leak threads?
    -- Is the problem even what I think it is (player arrived before character)?

    while true do
        if newPlayer.Character ~= nil then break end
        wait(5)
    end

    local humanoid = newPlayer.Character.Humanoid

    humanoid.Died:connect(function() onHumanoidDied(humanoid, newPlayer) end )

    -- start to listen for new humanoid
    newPlayer.Changed:connect(function(property) onPlayerRespawn(property, newPlayer) end )


    _G.stats.Parent = newPlayer

end

function Send_DB_Event_Died(victim, killer)
    -- killer may be nil
    local killername = "unknown"
    if killer ~= nil then killername = killer.Name end
    print(victim.Name, " was killed by ", killername)

    if shared["deaths"] ~= nil then 
        shared["deaths"](victim, killer)
        print("Death event sent.")
    end
end

function Send_DB_Event_Kill(killer, victim)
    print(killer.Name, " killed ", victim.Name)
    if shared["kills"] ~= nil then 
        shared["kills"](killer, victim)
        print("Kill event sent.")
    end
end



function onHumanoidDied(humanoid, player)
    local stats = player:findFirstChild("leaderstats")
    if stats ~= nil then
        local deaths = stats:findFirstChild("Deaths")
        deaths.Value = deaths.Value + 1

        -- do short dance to try and find the killer

        local killer = getKillerOfHumanoidIfStillInGame(humanoid)


        Send_DB_Event_Died(player, killer)
        handleKillCount(humanoid, player)
    end
end

function onPlayerRespawn(property, player)
    -- need to connect to new humanoid

    if property == "Character" and player.Character ~= nil then
        local humanoid = player.Character.Humanoid
            local p = player
            local h = humanoid
            humanoid.Died:connect(function() onHumanoidDied(h, p) end )
    end
end

function getKillerOfHumanoidIfStillInGame(humanoid)
    -- returns the player object that killed this humanoid
    -- returns nil if the killer is no longer in the game

    -- check for kill tag on humanoid - may be more than one - todo: deal with this
    local tag = humanoid:findFirstChild("creator")

    -- find player with name on tag
    if tag ~= nil then

        local killer = tag.Value
        if killer.Parent ~= nil then -- killer still in game
            return killer
        end
    end

    return nil
end

function handleKillCount(humanoid, player)
    local killer = getKillerOfHumanoidIfStillInGame(humanoid)
    if killer ~= nil then
        local stats = killer:findFirstChild("leaderstats")
        if stats ~= nil then
            local kills = stats:findFirstChild("Kills")
           local cash = stats:findFirstChild("Cash")
         local xp = stats:findFirstChild("XP")
            if killer ~= player then
                kills.Value = kills.Value + 1
            cash.Value = cash.Value + 50
            xp.Value = xp.Value + 3

            else
                kills.Value = kills.Value - 0

            end
            Send_DB_Event_Kill(killer, player)
        end
    end
end




game.Players.ChildAdded:connect(onPlayerEntered) 

game.Players.ChildAdded:connect(onPlayerEntered)

and something that goes in game.StarterGui.ShopGui.ShopFrame.IronSword.Main:

player = script.Parent.Parent.Parent.Parent.Parent
upgradeStuff = game.Lighting.ClassicSword
function buy()
if _G.cash.Value >= 10 then
_G.cash.Value = _G.cash.Value - 10
local a = upgradeStuff:clone()
a.Parent = player.Backpack
end
end
script.Parent.MouseButton1Down:connect(buy)

when i go ahead and buy the item,my main script for some reason only changes the tront gem value/money value but doesnt change the show the change in the leaderboard/stats. Can someone help me? Yes ik its a huge request!