1. Open PowerPoint file
2. Select a slide to reexplain
3. Click   to start presenting and recording  
4. "Esc" to stop (If unsatisfied please repeat the step 2-3)

5. Run [PowerCam/Edit Presentation] 

6. Deletion not satisfactory topic
    (using [Shift/Ctrl + mouse left button] to select multiple topics)

7. Moving the correct topic to appropriate position (MoveUp/Down)

8. Save