RTFM (pp 16 and 19), or look at hidden text below:
2. To enter the set up main menu hold down
both buttons until the main menu is displayed
Press select to choose the desired set up and
press mode to begin set up.
E = exit, return to ride mode
d = restore default settings
T= Test Mode
Setup modes 1-4 see <=== You want number 2 to set rolling Watts average
Press select button to
set rate of display for
watts. (rolling average)
Press mode button to
save.
Press mode three more times to skip the next settings, then press mode to "go do it"
To confirm that you got it right, go back in and make sure it's set to 5.