Why wont my start button work, and count for all players?

script.Parent.MouseButton1Click:Connect(function()
	for i,Player in pairs(game.Players:GetPlayers()) do
		local count = Player.PlayerGui.Start.count
		local Parent = Player.PlayerGui.Start.Start
		count.Visible = true

		Parent.Visible = false
		count.Text = 5
			wait(1)
		count.Text = 4
			wait(1)
		count.Text = 3
			wait(1)
		count.Text = 2
			wait(1)
		count.Text = 1
			wait(1)
		count.Text = "BEGIN!"
	end
	game.Workspace["start part"]:Destroy()
	wait(1)
	game.StarterGui["Start"]:Destroy()
	script.Parent.Parent:Destroy()
end

It's supposed to do that on everyone's screen, but it doesn't. The original worked, but only on the "player who clicked it"'s screen. Why?

Please ensure the this isn't in a "localscript" if it is, it will only run for the player who executed the script.

#Problem The Problem here is that you are using A LocalScript and trying to change something on other Clients (AKA Players). Because of FilteringEnabled this simply won't work. #Solution RemoteEvents is your Answer. For a guide of using RemoteEvents click Here. Basically what you want to do is ##LocalScript

1. Create a RemoteEvent in ReplicatedStorage
2. Connect a function to Listen for MouseButton1Click.
   • Which fires the RemoteEvent using RemoteEvent:FireServer()
3. When RemoteEvent.OnClientEvent is fired do the CountDown ##Normal Script
4. Connect to the Event RemoteEvent.OnServerEvent
   1. Which fires the Event using RemoteEvent:FireAllClients()
   2. And Destroys start part #Final Script LocalScript

script.Parent.MouseButton1Click:Connect(function()
	game.ReplicatedStorage.<REMOTE EVENT HERE>:FireServer()
end)

game.ReplicatedStorage.<REMOTE EVENT HERE>.OnClientEvent:Connect(function()
	count.Visible = true
 
        Parent.Visible = false
        count.Text = 5
            wait(1)
        count.Text = 4
            wait(1)
        count.Text = 3
            wait(1)
        count.Text = 2
            wait(1)
        count.Text = 1
            wait(1)
        count.Text = "BEGIN!"

    	wait(1)
	script.Parent.Parent:Destroy()
end)

Server Script

game.ReplicatedStorage.<REMOTE EVENT HERE>.OnServerEvent:Connect(function()
	game.ReplicatedStorage.<REMOTE EVENT HERE>.FireAllClients()
	game.Workspace["start part"]:Destroy()
end)