How do I change a SurfaceGui for everyone in an FE server?

Okay, so you need to put a LocalScript in StarterGui and a Script in ServerScriptStorage. You will also need to put the ScreenGui in StarterGui.

Yes, you will need RemoteEvents, so put one in ReplicatedStorage and name it what you want.

Now, in the LocalScript you will need it to fire the RemoteEvent when the player clicks on the ScreenGui element. It should look like this:

local ReplicatedStorage = game:GetService("ReplicatedStorage")
local RemoteEvent = ReplicatedStorage.RemoteEvent
local TextButton = script.Parent.ScreenGui.TextButton

TextButton.MouseButton1Down:connect(function()
	RemoteEvent:FireServer("VIP") -- The text you want to appear in the TextLabel
end

Now in the Script you will need to define what happens when the button is pressed.

local ReplicatedStorage = game:GetService("ReplicatedStorage")
local RemoteEvent = ReplicatedStorage.RemoteEvent
local TextLabel = game.Workspace.SurfaceGui.TextLabel

RemoteEvent.OnServerEvent:connect(function(plr, text)
	TextLabel.Text = text
end

That answer took me long to make so I'd appreciate if you marked this as the answer and gave it an upvote. Hope I helped you!