The student's Date of Birth can edited as long as a report has not yet been generated for that student.

From the VB-MAPP website:

1. Select the student from the Active Student Records list. 
2. In the Student section, click Edit Student.
3. Enter the correct Date of Birth.
4. Click Update.

From the VB-MAPP iOS App:

1. Select the student form the Student list
2. In the Student section, tap on Edit
3. Select the correct Date of Birth
4. Tap SAVE