Hello mr_easterner,
The reason it's not fixable is because it's not an issue at all. That's the way the display on the watch is designed to work.
An Apple watch uses the gyroscope and accelerometer to determine its orientation. When it determines that you have your wrist down and aren't actively looking at the display, it returns to the default clock display. The purpose of this is battery conservation. If the display were to remain fully on the entire time and needs to constantly refresh to display active things like a timer in the workout app, the battery would drain at a music faster rate. This would lead to a terrible user experience as you'd need to charge the watch so frequently, which is why Apple designs the watchOS software to work this way.
Now your display should come to full brightness when you're looking at it. Again the watch uses the sensors in it to determine the motion of you lifting your wrist and looking at it. If the display is not coming to full brightness when you do this, go to Settings > Display & Brightness and turn on the Wake on Wrist Raise option.
Turn on and wake Apple Watch
If you're using the always on display function, you can use these steps to manage those settings: Use the Always On feature with your Apple Watch
Cheers!
