I have a smart plug controlling a lava lamp in my bedroom that's been turning itself on at semi-random times for probably 6-8 months. Some old schedule that didn't delete properly, but wasn't displayed in the app anymore.
Took a whole 5min to reset and setup again; once I finally stopped putting it off.
Sigh... The fact that you have to ask.
Yes; you should always use your turn signal when you are turning. Just because you saw the arrow on the ground, that you are now stopped ontop of, doesn't mean everyone else is fully aware of your intention to turn. Hence, signals to indicate your intentions to those around you...