Sometimes users doing a particular shift like an "in charge" or "duty" shift are required to edit and update shifts, but only while they are doing that shift.
This is called a dynamic permission.
Dynamic permissions cannot be added to a permission group - they can only be added to users on a single basis.
How to add dynamic permissions to a user
choose the user from the staff list
choose "permissions" from the left hand profile menu
on the "additional permissions" column on the right click the plus button under "rosters"
4. you will see this dialog:
5. choose which shifts the user has admin permissions to, and which shift they must be doing in order to have these permissions
6. you can also add time before and after the shift that these permissions will apply