Hi David,
In your screen shot above the volume of the track is dictated by "VolCtrl" which is CC 7. If you want to permanently increase this, change its value which is currently 90, up to a maximum of 127. (I think you also have to change "VolNodeCtrl" to the same value as well - this is fairly new and I haven't quite got my head around envelopes).

The term "Velocity" is specific to each individual note on the track. You can see this alongside the note name in your track list above (either 85 or 90 in this case). This can also be a maximum of 127. If you record the track in real time using a MIDI controller it will represent how hard you press the key for each note you play. If you step record it will default to whatever value you set in Opt -> Other Options in the notation window.

If you are using a MIDI file created by someone else there may be "VolCtrl" changes embedded throughout the file and these will override any settings you make in the track window or the mixer. (Pipeline's screenshot above is an example of this). The author may also use "Expression" which CC 11 which will have the same effect.
Bob Norton provides a valuable list and description of MIDI Control Change messages here:
www.nortonmusic.com/midi_cc.html

If you check out the Mixer window, at the bottom you will see two buttons labelled "Ins" and "Del". They can be used to delete events and replace them with ones you set in the mixer. Hover over the buttons for an explanation of their actions.

I hope this helps.
Regards,

Richard Williams
Sydney
Australia