How do I deal with this teen?

I just turned 31. There is a young man in my volunteer group that I’ve known since his birth. I knew his parents when I was about 13. I am 13 years older than this young man. I have not seen them for 7 years until over a year ago. He is about 17 or 18 now. Anyway, since I’ve returned, he has been staring at me (with a serious look) and behaving rather strange around me. Without looking too much into it, he acts like a person with a crush. Everytime I am around, he’s distracted from whats going on by keeping his eyes fixed on me. But of course, I have no interest in this child. And he speaks down to me as though he thinks I am one of his peers. (I am told I look aroundage 22). A couple nights ago, he had the opportunity to arrange the microphone for me to give my presentation in our volunteer Group. Low and behold, my microphone sound was turned off, and I was completely humiliated in front if the group. Especially so after he handed me another one that was also not working. Afterwards, he said sorry while laughing and asked me if not hearing my voice in the microphone made me nervous. When I responded yes, he said sorry while laughing. A few people said he sabotaged the sound system. What do you make of this situation? And how can I handle it maturely?