If you’ve set the roll number prefix for a course as mentioned here, the prefix set for the course will be automatically applied to all batches under that course. If you do not want all batches of a course to have the same roll number prefix, you can change it for each batch. We recommend setting unique roll number prefixes for each batch. This will help you to identify which batch a student belongs to. The roll number prefix can contain a maximum of six alphanumeric characters.
At the top of your dashboard, click the module access icon > Administration > Settings > Manage student roll numbers to open the Manage roll number page.
Click View batches to view all batches in a course.
Click Edit roll numbers beside a batch.
The Edit roll numbers page is displayed.
Click Edit beside the roll number prefix.
Change the roll number prefix, and then click the Save button. The roll number prefix is updated for all students.
You can always reset the roll number prefix of the batch to the default course roll number prefix by clicking Reset to course default.
For more information, watch this-