Synfig Studio skeleton system is very hard to use

Hello. I have some problems with the skeleton layer. When I make a skeleton layer, and I link it to a drawing (an arm), one or two vertices don’t link. When I make the bone influence bigger, it links to the hand, when I already have a child bone for that. Can you fix this, possibly by allowing you to change which vertices are affected by which part of the bone, like you can in unity, in the sprite editor, with the weight brush. Thank you.