Double left-click on any compartment name to automatically assign enough crew
from quarters to that compartment to make it work. If there is no crew in the
quarters, the operation will not take place.
Right-click on a compartment name to send the crew to quarters (for rest and
recovery from wounds).

To easily move the entire crew (or as many as needed) from one compartment to
another, select the destination compartment (left-click on compartment name) then
right-click on another compartment name.
Note that right-clicking on individual crew members will send them to a selected
compartment.