Affect only AI who's inside the sphere collision?

We’re currently making a tower defense in school, so that means I’m spawning multiple AI’s from the same class.
And what I want to do is to have this bool to be set to true for the AI’s that are currently inside the sphere collision.
But I’m unsure what nodes I’m looking for. So far as soon as the first AI enters the collision, it sets the bool to true for every other AI within the class.
How can I seperate these AI into individuals rather than affecting the entire class?