To adjust ticket availability for a timeslot:
Go to your calendars: click on Catalogue > Calendars.
Open the Date view calendar
Find your timeslot
To change capacity in bulk, select the timeslots and click on Actions > Change capacity
To change the capacity of a single timslot, go to the capacity column > Click the pen icon next to the capacity number
Use the – / + buttons to decrease or increase the number of available tickets
Click Confirm to save your changes
The value in the Available column will update accordingly.