No.
Every time you turn left or right, or switch lanes on a highway you should use your turn signal in your car.
When merging, you should use a turn signal. In any situation in which your movement could affect another car, you should signal. Not to do so is a moving violation.
Check your mirrors and signal your intentions.
Use your turn signal to both pull out of and return into the lane. Motorists should not signal their intention to pass by flicking their high beams.
To allow others [drivers and pedestrians] to know what we intend to do.
So that traffic behind you is able to anticipate your turn, and can act accordingly.
You should use your turn signal in far enough advance so the car behind you knows you are going to turn and has enough time to slow down. However, putting the turn signal on too far in advance can be confusing because the following car will not know exactly when you are going to turn.
I guess you should only use it sometime then.
Your question makes absolutely no sense. However, I think you may be asking what to use if your turn signals do not work. The answer is to use hand signals.
You could be hitting the flash feature on the turn signal arm when you use it.
We could use a little more info here. The turn signal light? In front? In the rear? The turn signal switch?