1. First, go to Core > Settings > School Information > Years & Terms.
  2. From the Selected Year drop down, select the school year for the summer term.
  3. Note the start of that school year.
  4. Then, go to Core > People Finder, and locate the user.
  5. Click the Access tab. 
  6. Click the Edit Pencil and Edit School Enrollment
  7. Edit the Enrollment row for the summer term in question and change the Enroll Date to the same date as the start of that school year
Tip: This will make the summer term's transfer course(s) show before the start of the school year on the transcript.