Hi Alex,
Save the scene, preferably with a new version number.
Take your character to the Bind Pose (Weight Tag> Attribute Manager). Use the twirl-down triangle, then click)
Switch the Skin object off.
Set your Joint(s) as you need it 9
Set new Binding pose (Weight Tag> Attribute Manager). Use the twirl-down triangle, then click)
Switch the Skin Object on.
.
Typically, I encourage to explore this first on a simple setup, a cylinder with a few joints
Cheers