To specify the last day of the current period:
- You can continue to mark the days that you are bleeding by using the "bleeding" toggle. Thus marking all the days including the last day of bleeding.
To change a previous period date:
- Select the date that you marked as "First day of period" and unselect the toggle
- Select a new date and mark it as "First day of period" This will allow you to change a previously marked period start date
here are some screenshots for reference.