All the report definitions in Disk Triage are stored as external files. When a report is requested, the program loads the appropriate report from the 'Reports' directory directly under the installation directory (Disk Triage). If you make changes this is the default directory the program will save to.
However, the program also ships with a copy of all the reports held in the Report sub-directory under the Templates directory. These are held there in case you need or want to go back to the original format of the reports.
Directory Structure
Disk Triage
Reports (Active Reports)
Templates
Reports (Your backup of the original reports)