How can i change the weight of a bone ?

Hi, i’m begginer at 3DS Max and i have a problem with the weight, i follow tutorial on youtube but what they do, doesn’t work with me.
I will try to explain.

For choose the weight they use the option “Edit enveloppe” and change on the playermodel the enveloppe and it’s affect the weight, but for me the weight isn’t affected.

I would to affect the weight of the finger 2, 3 fingers :

I have the weight on the left of the picture and i need to have as the right of the picture but it doesn’t work.

Thanks for the reading and maybe the helping. ^^