This should fix the problem permanently.

Seat Memory Settings
Some owners have had trouble getting their driver settings to save. Thanks to another owner, we’ve learned that this is the best process:
• Start your Corvette and select “Settings” on the Infotainment screen.
• Scroll down to select “Vehicle;” then select “Comfort & Convenience.”
• Select “Auto Memory Recall” and turn it Off.
• Back up one menu to select “Easy Exit Options” and turn this Off as well.
• Adjust your seat, steering wheel and mirrors to your preferred driving settings.
• At the same time, press the “Set” button and the “1” or “2” button. A beep will
sound to confirm your settings.
• Move the steering wheel up and the seat back as far as it will go; then move the
seat forward about a half-inch. At the same time, press the “Set” button and the
“Exit” button. That same beep will indicate that your setting was saved.
• Go back to the Infotainment screen and turn “Auto Memory Recall” and Easy Exit
Options” back on. The next time you get into your Corvette, the settings should work.

My ‘15 Z51 started doing what you described out of the blue. You’re not out of your mind. This is definitely a real problem. ...and all the “quick-fixes” won’t restore the erratic mirror operation when recalling memory on start or exit when either option is set. I have found when I only use the door switches for memory recall, the mirrors stay put. My dealer can’t figure it out either. Only my driver’s side mirror drives to a random position. I have replaced the mirror control module in the door and the mirror actuator in the mirror. The dealer has reprogramed the memory seat module under the driver’s seat to no avail. Next I plan to replace that memory seat module - which will require programming. Here’s a link to my older post:

https://www.corvetteforum.com/forums...all-issue.html

Funny! I sent you a PM