changing a variable from true back to false?

im trying to set the variable (myboolvar) from true back to false after i press a onscreen button to prevent the button from being pressed again but that is not the case as i can still press the button as many times as a want so could someone help me to fix this? (line 15)

local myboolvar = nil
myboolvar = true
if myboolvar == false then

end
if myboolvar == true then
	local button = script.Parent.Frame.Thebutton

	button.MouseButton1Click:Connect(function()
		TypeSound:Play()
		typewrite(textLabel, "Click the button to continue.",0.1)
		TypeSound:Stop()
	end)
end
myboolvar = false