Diagnosis
The microwave lacks a backup battery for the clock circuit. Power interruptions reset the clock to default settings.
How to Fix It
There is no fix to retain clock settings during power loss. This is a design limitation. Use the clock set function after power restoration. Press "Clock" button, enter time, then "Start" to set.
If That Didn't Work
Ensure the microwave is plugged into a stable power source. Consider using a UPS for critical applications, but this is not typical for microwaves.
Heads Up
The clock reset does not affect cooking functions. The microwave will operate normally once power is restored.