I installed OM 7.2 in Ubuntu 20.04. I tested changing some preferences and some of them aren’t saved.
For example these changes were saved:
Appearance tab, default presentation → list
MIDI tab, Default score player → fluidsynth
And these ones weren’t:
Score tab, Music Font Size → it is always 24, other won’t save
FluidSynth tab, Load Synths → it appears always as “Unloaded…” so I have to load it manually every time I open OM. After loading it, it works fine.