The ability to bulk change Enrolment Staff is facilitated via the Data Insights Manager.
If you were to create a query to display a list of enrolments, you can then choose to amend the Staff Members attached to those Enrolments via the following steps.
An example query could be comprised like so:
This will return a list of Enrolments within the selected period.
On this following screen, I can then choose to replace Enrolment Staff:
In this example, I have selected to add two staff members, and mark one of them as the Primary Staff Member.
Pressing Finish will then update the selected Enrolments to reflect the changed Enrolment Staff.