The interviewer is looking for someone who has good leadership skills and who knows how to troubleshoot. If you notice a staff member having trouble doing their job, there are a few things you can do to help. First, try to understand what might be causing the difficulty. It could be they struggle with a particular task or process, or underlying issues could be affecting their work. Once you better understand the situation, you can offer support and guidance. Explain when you had difficulty training a staff member and what you did to resolve the issue. Be sure you do not talk negatively about the staff member, and describe how you turned a negative situation into a positive.