Ah, the old "sextuple post"...

Anyway, the Velocity Midi FX plugin (which can be dropped on to MIDI tracks, and should have a red UI) has four different modes - what you want is the "Set to" mode, which should take incoming notes and set their velocity to whatever value is in the vertical meter below the "Set to" text; this should accomplish what you're trying to do.
However, that effect won't change your recorded notes, only the notes that are output from the track. In order to "render" the effect and actually modify the note data you have to right click the MIDI clip and do
Process Effect -> MIDI Effects -> Velocity and make sure the mode is "Set to" and the value is what you desire.
The more straightforward way to do modify data (which you may have to do if Process Effect isn't in Home Studio) is to select all notes in the Piano Roll view, and then in the velocity editor scale them all up to 127. Now they are all uniform and can be drag scaled as a group to whatever value you like.