game.StarterGui.ScreenGui.TextButton.MouseButton1Click:Connect(function()
game.StarterGui.ScreenGui.TextButton.Text = ("Clicked")
wait(1)
game.StarterGui.ScreenGui.TextButton.Text = ("CLICK ME.")
end)
I'm new to programming in Roblox Studio so I am probably doing a simple mistake.
Your issue here is you are using a script underneath Workspace instead of under StarterGui.
You will notice when you test a game that all of the items under StarterGui get moved under the Player objects in "Players". You need to move move this script inside of the ScreenGui and reference it as follows:
-- Parent object
local screenUI = script.Parent
screenUI.TextButton.MouseButton1Click:Connect(function()
screenUI.TextButton.Text = ("Clicked")
wait(1)
screenUI.TextButton.Text = ("CLICK ME.")
end)