Units under the computers control

[Wolfleader]

I've found that having some platoons under computer control is a good way for having a good thorough means of having all the units under my command to automatically attack enemy units within their weapon range without me having to tediously scroll through all of them one at a time, select a target and fire (quite tedious when you have a sizable force under your command).

The problem is whenever I do this, the computer also begins clumsily advancing them towards the objective hexes. I only want the computer controller to engage enemy units without moving any of the units under its control. How do I accomplish this?

Thanks in advance.

Note: I've tried setting C&C on and putting all of them on the defence stance but the computer still moves them.