Volunteer Check In Setup
Go to Volunteers-Check In Setup

Image: Check In Setup
Choose your default location and define check in mode/type.
There are 2 types: quick or extended (preview volunteer details (contact info, photo,...)

Image: Location and Type
Select Individual or group check In

Image: Individual and Group Check In
Start to type users/group name, select it from dropdown list and click CHECK IN button

Image: Dropdown list