To customize the Control Center, swipe up from the watch face, scroll down (you can do this with the crown), and tap Edit. The icons will start jiggling, which means you can drag them into any order you like. When you’re done, just tap Done at the bottom of the screen. While you can’t remove icons from the Control Center, you can move the least used ones to the bottom, as just 6 icons appear on the screen without scrolling.
I had an Apple Watch for years before I knew you could do this. And then the other day I lost a few minutes trying to long-hold on the icons (like you do on Home) to get them to jiggle because I’d forgotten to scroll down to find “Edit”.
Immediately I moved DND to the top left, and it’s been great.