cant change skinned mesh renderer root bone

I am trying to swap the mesh on a generic first person arms asset. I did change the mesh in the skinned mesh renderer and it completely disappears. Also as per my test changing the rootbone of any skinned mesh renderer does absolutely nothing.The new asset moves with its own root bone if in the scene. I even duplicated the new rigged mesh and chjanged the root bone of one mesh renderer to another and still the meshes deformed wioth their imported bones only. What can i do to swap meshes outside of code? I just want to change the appearance that's all. @Hellium @PictonicStudio @robertbu