Scratch

I've never personally done this before but i'll try to help.

If the enemies are "standing still" and the world is moving then you would expect the enemies to move with the world so that from their point of view they aren't moving.
To do this you would have to move the enemies WITH the world.
If you are using the scrollX method to move the world then simply move the enemies by that much as well 

Hope thats clear enough 

Use that script where they move with the world, and then make a variable called "Xpos" or something similar.  Have a block that looks like this:



As you can see, it's X and Y positions are affected not only by a scrolling variable, but by this new variable.  Changing this new variable while the script is active is the same as having it move, even when scrolling.

Note: When scroll X and Y equal 0, these new variables will be their true positions, but then they are affected by scrolling.