La Crosse Technology WS-9031U Instruction Manual page 39

TOGGLING AND RESETTING THE OUTDOOR RECORDINGS:
1. To toggle between the outdoor current, MIN/MAX temperature and
humidity data and the times (for temperature data only) they were
recorded press the MIN/OUT key:
Once to show the MAX outdoor temperature and humidity data with the
recorded time and date.
Twice to show the MIN outdoor temperature and humidity data with the
recorded time and date.
Three times to return to the current displayed values.
2. To toggle between sensors, press the CH/+ key:
Once to show sensor 2
Twice to show sensor 3
Three times to return to sensor 1
Note: The sensor number will only be displayed if there is more than one
sensor being used.
3. To reset the MIN/MAX outdoor temperature, and the time at which they
were recorded, press and hold the MIN/OUT key for about 4 seconds.
This will reset all MIN/MAX data recorded to the displayed values for
that particular sensor.