I downloaded WUHU and have it running on a Windows XP Pro machine but can't find where to change the outdoor setting to read channel 1.
Look in the WUHU folder for configuration data.ini file Open it up and look for WMR968 Outdoor Sensor=0 Change the 0 to a 1
Be sure the program is not running when you make that change.
You may want to save all the text in that file to a text file so you can see how it's laid out. You can also change upload times and delay the program launch times and stuff by tweaking some of the numbers in that file.
Good luck!

EDIT: Here's a link to the WUHU help file:
http://www.lissproductions.org/wuhu_manual/the-wuhu-software-manual/the-wuhu-configuration-ini/