To set the planned fuel for a trip, look in the Flight Details window. That's where you set this sort of thing, and you just click on the blue planned fuel hyperlink to show a slider that lets you change it.
Hope this helps!
Is it possible to show the aircraft reg and type on the PLOG to confirm that you have selected the correct aircraft type for your planning and that the parameters are valid for this flight?
Also how do you set the Fuel On Board figure for the PLOG and can it be amended?
Tidders