How do you select thrust modes on 737 NG?
 

I'm not a pilot, but am a maintenance instructor on the 737 Next Gen. I want to know how you jet jockeys select another thrust mode. Is it automatic? On the 757, you do it at the thrust mode select panel, on the P3 panel. Please be kind and not use too many acronyms in your answer, as maintenance folks don't always understand the jargon that is used in the flight deck! Thanks for your help!