How to edit models in Unity?

I am having a problem with a model in Unity, or actually most models I come upon.

When I import the model(s) (.3ds, .obj, .fbx, etc) everything works fine. I have the materials and textures all set and ready, but one thing that usually occurs is that the model(s) is always in the same position.

They all seem to have their arms sticking out from their sides, like action figures… When I seem images of them posted on the download source, or even in-game from other games, they don’t seem to have their arms sticking out like they want to give out a hug.

So I’m asking if there is a way to edit this in any particular way on Unity? If not, on Blender or some other 3D program?

For example: I have a Slender Man .mdl file from gMod exported into a .obj file. I import it into Unity and everything is working well. There are 4 body parts on this model: 1 for both of his hands, 2 for each half of his face, and the last one for his entire body.

I can move, rotate, do anything with this body parts, but the arms are stuck with the entire body, from neck to feet. It would look rather stupid to have Slender Man chasing after you with his arms out ready to bear-hug you. I need to put his arms down to his sides, so he can stand normally, or in this case, standing menacingly.

If anyone can help answer my question or point me out to a different forum answer/tutorial, it would be extremely appreciated!

OBJ does not support the skeleton. Use 3DS, FBX, or Collada or Blend instead. When you import that, you’ll see some object in it like ‘root’ or ‘hips’ or something, and expand that to track down the skeleton to the parts you want to move (shoulders), then rotate them. Better yet, get someone to animate the thing for you and import that.