How to turn off auto-attack and Guard Postions?

Hi, I just joined this forum
So I'm making a map, and I can't seem to figure certain thing...

When my unit notices a target in range, it automatically attacks it. I don't want it to do so.
I've tried to change the Combat - Acquistion Range in Object Editor to 0.00 or to 0.01, but this doesn't work. I realize I could change the unit into a worker, but I don't want to do so, because there is an icon in left-bottom corner if I do so.
Can I do this somehow?

Another problem is, when I order an unit to move somewhere via triggers, the unit will change its mind after a while and returns to its original postion. Is there a way to make it obey my orders?
Thanks for any answers :P

Try giving that unit permanent invisibility with a fading time of -1 and auto-acquisition (or something like that) off.

Add the worker classification to the unit(s) at runtime using triggers, and the icon will not appear.

I don't think it's gonna work, however the opposite will. Set the worker classification to the unit, and to remove the 'idle icon', just use call UnitRemoveType( myunit, UNIT_TYPE_PEON )

Worker classification however is not really 100% safe either. Workers will still auto-attack other workers.

That invisibility method worked for me nicely. I'm not sure if it stacks with other invisibility effects though.