Light will keep coming back.
You need to bleed the system when adding coolant to turn off the light.
There's a black plastic + screw next to the cap. Or near around it. Fill the coolant when engine is cold to recommended level. Close it back up. Start the car. Let the car warm up. Start unscrewing the black screw slightly till hot air and coolant start spilling out. When there's nothing left to spill out. Close the screw. Turn off the car. Let the car cool down again. Fill to recommend level again.
This get rid of all the air bubbles inside the coolant system which is causing the light to come on.