why does my hips and ribs move when i am in pose mode and I move the arm Hi when im in pose mode I rotate my arm you know to go up and down and my hips and ribs area would expand looking very awful i want it so that my body stays still if my hands are rotating im talking about blender  not irl I believe the problem is caused from weights however i could be wrong you can notice from this picture that the sides of the character come out his ribs/hips area plz help
You need to go into weight painting mode (click your model first, not the armature), shift right click on your arms/hands, and use the subtraction brush to remove the color from the areas you don't want to move.