It's most likely in Auto Range mode. Since it's continually changing ranges, the front display cycles each time continuously. To fix this, turn Auto Range OFF.
The WT300 offers high performance and high reliability in a compact package with excellent price value, making it ideal for multiple applications from R&D to manufacturing test. It is the fifth generation of Yokogawa's value series power meter, and the world's best selling power meter.
Measure characteristics of devices that generate, transform or consume electricity. Also called power meters or wattmeters, these devices measure parameters such as true power (watts), power factor, harmonics, and efficiency.