How coould I scale a bone to fit inside the models body? the bone is too wider than the models body(hand) and it is giving me a trouble while weight painting(the model shrinks). And when I try to resize/scale the bones it doesn't go as I needed it(unable to make it thiner with out affecting the length). I don't get the problem on vertical bones. only when adding horizontally the bone gets wider than needed.
You cannot scale the default armature but if you change the bone display type to B-Bone, you can use CtrlAltS to scale it and make it thicker or thinner. It's also fairly easy to have the default armature display type fit inside any model by scaling it down in Edit mode and making it longer and thinner.