Destroying

I often copy and paste objects to multiply them on the frame. When my event calls for one to be destroyed, one of two things happen: either the right one is destroyed, or every object of that type is destroyed. How do I change this property of the object?

Whether one or all of the objects on the playfield are destroyed depends on which objects are selected by the events - in general, if an event directly mentions a specific object, then only that object will be affected by the actions.

Some conditions are more subtle about this than others - for example, the condition "[Object]'s Alterable Value A is equal to 0" (as selected from that object's sub-menu in the New Condition window) would select just the objects that matched that condition, but doing the same thing by putting Alterable Value A("Object") and 0 on the two sides of a Compare Two General Values condition wouldn't select specific Object instances, and would apply the effect to all of them.

Could you tell us what you need?

You could do something like create the objects when needed instead of copy+paste, or clone them (different from copying), depending on your objective.