In the general property settings you can choose how you would like to have your reservations assigned on the calendar.
You can choose to have them assigned either automatically to the first available unit of the booked unit type or you can assign them manually.
In case of setting the manual assignment, each new reservation will be on the unassigned list, but it will occupy availability on the calendar.
The unassigned list is placed on the upper right corner of the calendar and by clicking on the desired reservation the “Assign unit” window will appear. You can choose either to assign a certain unit for the duration of the whole stay, or if the availability on the calendar does not permit you to have the same unit for the entire stay, you can split the reservation on more units.
Once you have assigned the unit to a reservation, that reservation appears on the calendar, while on the reservation details you will see which unit or units are assigned to it.
Needless to say that you can change the unit if necessary.