There are two types of units in this mod, one behaves like a lamp, that just shows you the status of the circuit, the other one behaves like a speaker that generates the alert as well. The alert stays on until the condition changes.
What is your usage, the lamp type unit does not work for your circuit? Or you do want to alert only on the map not the small icon? Or should it should only stay on temporarily?
Edit: I understand what you need now, that is unfortunately a core game engine "issue". Currently there is no way to only have alert on the map without that small blinking icon, only the other way around (no map alert, only blinking icon). You can maybe try to request this feature from the Factorio devs.