Oh, so this is a bit more complicated. because it's a fully animated scene. If you click on "Alex" for example, and then on the "Plugins" tab, you'll see that this scene is using the "VamTimeline" plugin, which is a keyframe editor for animations. You can click "Open Custom UI..." for that plugin, and you will also see that each animation step ("Grind", "Grind Slow", "Grind Fast" and so on) has a set of keyframed positions for different controllers -- hands and head of "Alex" included. So whenever you try to change their position/rotation, the plugin will "reset" their position at certain keyframes.
To "unlock" Alex' hands for example, you can just click on their "Controllers" within the Custom UI of the Timeline plugin, which will "disable" them for that animation, and you can freely move those limbs around while the animation is stopped). If you want to be able to move them WHILE the animation is playing, you need to select a keyframe and then disable the "Position" and "Rotation" checkboxes for this specific limb...
But then again: this might be too much work for this scene -- because you basically have to change all the ~20 animations, because once switching between them, the hand(s) will go back to their original position...