For sound volume from MIDI, there are more layers of control that can affect volume.
You can control the overall volume of the synth that produces the sound by boosting it to 127 (on the synth volume itself and in the DAW) as mentioned.
The next layer down is the 'Velocity' of the events sent to the synth itself. If the keyboard used to record the MIDI was played/recorded with low velocity, the volume may still be sub-par even with the synth turned up .. because the synth isn't being told to play that particular note loud in the first place.
In RB, increasing the velocity is a pretty easy option in the edit area.
Note that 'velocity' can actually also affect timbre; some synths can sound a note differently if you hit the key hard vs. playing lightly. Even better synths may actually allow changing the whole patch/sound depending on the velocity of the MIDI event.
Next up: aftertouch and polyphonic atertouch
https://en.wikipedia.org/wiki/Keyboard_expressionYou can change the sound with keyboard pressure even after the initial velocity.
MIDI is cool!