Scoutbook now links directly to the training reports at my.scouting.org. Training updates are done there.
A unit key 3 member (unit leader, committee chair, or chartered organization representative) or a delegate setup in Organization Security Manager can credit training for adults in their unit via Training Manager at my.scouting.org. Login to my.scouting.org, click on menu, click on unit, click on Training Manager.
A tutorial for Training Manager is here.