Use Rapid Edit to change schedules for assignments in the Timeline panel or use the edit assignments panelA contextual panel used to manage schedules for resources and projects on the Resource and Project Planners. to view and change schedules for assignments and held resource requestsOccurs when a named resource has been reserved (held) against, but not booked to, a project or opportunity. Also referred to as "soft booking"..
To edit assignment hours per cell:
You can drag the assignment bar horizontally to make changes to the entire assignment schedule.