Easiest way to make difficulty work with Listeners?

This is my first project in unity.
I'm making a simple 2D shooter game. I'm planning to be able to increase difficulty via a slider in the opitions menu. The slider will affect the opponents health possitively and the player's health negatively. I already figured out how to load and save the slider's value, but I'm a little uncertain about listeners. How am I supposed to implement a trigger that trigger when I hit my Okay button in options. It should change the health value in all the monoscripts.
Or should I just extract raw value from the database?

 

The class that saves and loads your games config values can contain the Unity event that the listeners are listening to. Anytime the class performs a load or save it can call the Invoke method of the Unity event to notify all listeners that the values may have changed.

 

Wow man, don't get ahead of yourself with complications!!!!

Just keep it simple, get it working first.

- connect the slider to a persistent property. Your description sounds like it would be a GameManager type construct, or perhaps a player preferences type construct.

- use the value within your game to change the behavior

That's it. Don't start focusing on "listeners" and "databases"... it would be like worrying about what type of air the gas station is using to inflate your tires. Who cares? Just go drive.