To influence playback in more detail, you can include MIDI events in your music. You can use this to (invisibly) give the synthesizer MIDI commands such as instrument selection etc.
The instrument file lists the options that can be used in the menu (sustain, chorus, portamento, vibrato, sostenuto).
An instrument change (program-change, C0) in MIDI channel 4 with a Tuba (no. 58, hex 38) as general-MIDI instrument yields in hexadecimal notation: C3 38.
With <shift-M> you can add any MIDI event as you see fit. You do need to know exactly what you are doing and be somewhat familiar with hexadecimal arithmetic...
A pitch change (pitch-bend, E0) of a quarter tone higher is made with E3 60, restored with E3 40 in midi channel 4 (channel 4 becomes lower in MIDI 1: 03, 03 +E0 = E3)
On the notation bar you will find MIDI events marked with a blue block, the content of which is visible on the status line (0 MC4 72 00) in case of an instrument change (C0) to steel drum (72) in midi channel 5 (04).