My TextLabel's text doesn't change when I run this script?

I'm building an airport with a friend, and I want to make a single main script that handles all the functions that the airport does.

There is a SurfaceGui in the airport that shows departure times (in seconds). I managed to make a NumberValue stored in a Folder count down, but I need to make it so the time shows on the screen as well.

My friend somehow did this without using tostring() for the NumberValue, but he used multiple scripts, which I want to avoid, since it's very unorganized.

Below I'll post my script and then my friends' scripts. These are normal Scripts placed in Workspace.

My script:

local airport = game.Workspace.Airport
local booths = game.Workspace.Airport.Booths
local screen = game.Workspace.Airport.AirportTV
local screen2 = game.Workspace.Airport.AirportTV2
local times = game.Workspace.Airport.DepartureTimes

-- air canada departure times
while times.AirCanada.Value > -1 do
	wait (1)
	times.AirCanada.Value = times.AirCanada.Value - 1
	if times.AirCanada.Value == 0 then 
	times.AirCanada.Value = 120		
	end
end

game.Workspace.Airport.DepartureTimes.AirCanada.Changed:connect(function()-- numbervalue
	local val = game.Workspace.Airport.DepartureTimes.AirCanada
	local label = game.Workspace.Airport.AirportTV.TVScreen.SurfaceGui.AirCanada.Arrival
	
	label.Text = tostring(val.Value)
end)

Friend's scripts

--script 1
while wait(1) do
	script.Parent.Value = script.Parent.Value - 1
	if script.Parent.Value == -1 then
		script.Parent.Value = 120
	end
end
--script 2

while wait() do
	script.Parent.Text = script.Parent.Time.Value
end

My friend has a habit of making scripts "while wait() do" -_-

This is how your script looks:

local variables = values

while wait(1) do
	-- stuff
end

AirCanada.Changed:connect(function() end)

The while-loop will go on forever. The code after the loop will never run, so the AirCanana.Changed:connect() neither. A simple fix would be connecting the event before starting the while-loop.

A combined version would be this:

local airport = game.Workspace.Airport
local booths = airport.Booths
local screen = airport.AirportTV
local screen2 = screen.AirportTV2
local times = airport.DepartureTimes
local tvscreen = screen.TVScreen
local gui = tvscreen.SurfaceGui

-- air canada departure times
while times.AirCanada.Value > -1 do
    wait (1)
    local value = times.AirCanada.Value - 1
    if value == 0 then 
        value = 120     
    end
    times.AirCanada.Value = value
    gui.AirCanana.Arrival.Text = tostring(value)
end

Although it is advised to use WaitForChild.