DIAGNOSIS This model doesn't have a backup battery for the clock/memory. It relies on constant, minimal standby power from the wall outlet to keep the microcomputer's memory alive. Even a half-second power interruption will wipe it.
FIX There are two angles. First, check the plug. 1) Ensure it's fully and firmly seated in the outlet. A loose connection can cause tiny dropouts. 2) Try a different, known-good kitchen outlet to see if the problem follows the microwave. If it does, the issue is likely just your home's power stability. The only true "fix" is to plug the microwave into an uninterruptible power supply (UPS) or a quality surge protector with line conditioning, which can bridge very short gaps in power.
IF THAT DIDN'T WORK If the clock resets even when there's no noticeable power flicker in the house, the internal power supply board might be failing to maintain the standby voltage. This is a deeper electrical fault that would require board replacement by a technician.
HEADS UP This resetting doesn't affect the cooking functions or safety. It's just an annoyance. The programmed settings (like clock time) are stored in volatile memory, so they need constant power.