How do I mark a group of advancements as awarded (SB)

From the Troop, Pack, Patrol or Den menu, select the Needs Awarding report.  You can select advancements there and then click on the Mark Awarded bar at the bottom to mark them as awarded.
If you mark advancements as awarded by mistake, see the guide here on how to undo it.
https://help.scoutbook.scouting.org/knowledge-base/how-do-i-mark-an-advancement-un-awarded-sb/