Playing Sound for one player?

When game runs sound plays normally, but when you click button it doesn't stop

game.Players.PlayerAdded:connect(function(plr)


            local startsound = plr.PlayerGui:FindFirstChild('Sound')

            if startsound then
                if startsound.Name == "BackgroundMusic" then
                    startsound:Play()
                end
            end

        game.StarterGui.ScreenGui.StartFrame.PlayButton.MouseButton1Click:connect(function()
            local stopsound = plr.PlayerGui:FindFirstChild('Sound')

            if stopsound then
                if stopsound.Name == "BackgroundMusic" then
                    stopsound:Stop()
                end
            end
        end)
end)