How do I set a unit on scmdraft2 to hold its position and not move. im using a critter so im not sure if its able to or just set to junk yard all the time.

actually im very sure that if the critter is not owned by a neutral player and it is preplaced on the map and not created via triggers, it will not move.

ive tried having it preplaced as a Player 9 unit but it still seems to roam around. Ive tried switching between p12 to another player but was unsuccessful as well.

Quite true. Also, if it is owned by a neutral player 1-8 it won't move.
Alternatively, you could center a very small location on the critter and constantly move the critter to the location or order the crittter to the location. If you need it to be attack-able, move will not work so well since the critter will dodge many of the attacks, but
'order' should work fine.

Ok thank you for the adice. it wouldnt work preplaced for P9 but 1-8 seems to work perfectly.

You can do a similar effect of hold position by constantly moving that unit to an unwalkable location like doodad or water. The unit won't be able to move but it will still be able to attack. Duplicates the "tower units" like in Warcraft 3.

This topic was about a similar problem, although it's answered better in this one(which is linked to in the first one).

I like those ideas as well. very helpful. i came across another problem as well. i want to modify a unit to be "blind" when i send it to a certain location and modify it again to no longer be "blind" when leaving that location. is that possible?

Only way to do that is by getting a computer to do it through AI, check out this wiki on doing that, but it's not extremely reliable, so you may not want to.