The collided behaviour gives 2 outputs. Object A ID and object B ID
Object B would be the coin you collided with
Use modify array behaviour to append object B ID to an array (get coinsArray attribute).
Save that array to file and change coinsArray attribute to the array as well (set coinsArray attribute)
At the start, load collide array from save file and loop the array.
Use get array item with index "loop index"
That will be the coin ID. Set an attribute to tell it's already been collected, change the color, etc.