If one or more application form approval statuses have been defined, security rights can be used to limit how and when a user can change the approval status of an individual application.
Within each user's security rights, on the Tools tab, you'll see the grouping "Application approval form statuses". Listed here are:
One right for every valid status transition. That is, for every approval state, a right for each state that an application in one state can legally be changed to.
For every approval status that requires one or more eligibility/intake checklists, the option "Override eligibility checklist requirements for XXX".
Plus two special rights:
Change any approval status to any other status. With this right, a user can change an application's approval status to any value regardless of the current status or the rules for changing statuses.
Reduce the approval status of any application. With this right, a user can change an application's approval status to anything lower than what it currently is.
With judicious use of these rights plus the rules of application form approval statuses, you can establish a defined workflow for managing how volunteers are approved.