How do I customize Apple Watch app display and timer sound

I’m using an Apple Watch Series 4, and I’ve noticed that when I have multiple apps running—such as the Workout (Outdoor Walk), Timer, Stopwatch, and Fitness apps—the watch defaults to displaying the Stopwatch on the screen. However, I’d prefer to see my Fitness app (specifically my activity rings) instead.

Is there a way to change this behavior so that my watch prioritizes showing the Fitness app rather than the Stopwatch? I’d appreciate any guidance on adjusting these settings. Thanks!

Also the timer app has an awful dinging sound. I would rather have this changed to maybe a sonar or futurists digital sounds. and also metal gear solid sounds as part of the sound library would be great, lots of people desire metal gear solid sounds:

[Re-Titled by Moderator]