..I can`t stop my chin from moving when I`m tonguing. Can someone please give me tips to stop this?

I have been playing clarinet for eight years now but I can remember when I started that I had the problem that I used to have. The thing that you need to do is to tighten the corners of your mouth to tighten the embrochure. That should help because I got the info from a private instrutor when I was learning a it helped me a lot.