why is this destroing all enemys instead of just one?

you could try removing that second Collision condition.

Enemy HP <=0 will suffice as the condition and Fusion will automatically scope and destroy the correct object without the need for the bullet colliding with the enemy condition.

The events are getting generalized . Although I don't really see anything wrong there. But you might want to try removing the collision condition from the hp <= 0 event. As the above event would set its HP to 0 or lower eventually making that event true and destroy it without with that condition anyway. Maybe thats whats generalizing it. You could also use the debugger to ensure that all enemies have their own independent values for HP.

Edit: DaveC beat me to it.

Use a For Each loop to check each object individually (see example attached).

What's going on in the bonus loop? If that refers to the enemy that will be causing it.

A) as the other said, remove the collision event.
B) I would double check your object values, sometimes i miss to either change the value or set the correct amount. Is your HP set at 20? Is the Damage of the ship at 10 or -10? etc.

I believe your bonus loop is resetting the object scope. Did you try moving the start loop action to AFTER the destroy action?