You mean roundabouts ? In France ; you must use your signals, (we drive on the right side of the road remember) if you turn right, you must indicate it ; if you go straight you don't need to signal it when you enter the roundabout, only when you exit it ; if you go left (so more than 180° from the entry of the roundabout) you must signal it and position yourself on the left lane of the roundabout and use your signals (left ones when you enter the roundabout) and when you exit, you must use the right ones again. If you are going back (demi-tour) then same, you must signal it straight away (so left lane straight away and left signals) and then to exit, go back on the right lane and put the right signals.
Nice truck
I'm curious why some people use their turn signals at traffic circles
You mean roundabouts ? In France ; you must use your signals, (we drive on the right side of the road remember) if you turn right, you must indicate it ; if you go straight you don't need to signal it when you enter the roundabout, only when you exit it ; if you go left (so more than 180° from the entry of the roundabout) you must signal it and position yourself on the left lane of the roundabout and use your signals (left ones when you enter the roundabout) and when you exit, you must use the right ones again. If you are going back (demi-tour) then same, you must signal it straight away (so left lane straight away and left signals) and then to exit, go back on the right lane and put the right signals.