Yamaha EZ-220 keeps reverting to being LOUD

[SeaGtGruff]

Michael, thanks a lot for your (exhaustive) answer that pretty much wraps up everything for me here.


Which is key. It just wasn't possible to get what I wanted (overriding the power-up volume) from the start.
Everything else, including the 'Update'/reset idea was an aberration.

Ironically, I can't even any longer recreate the 'problem' of the keyboard reverting the 'M.Volume' value when I navigate away from the menu entry. I hadn't even initially been completely sure about this observation (see post #1), and I'm not able to provoke this behavior (if it ever existed) now. The value being reset after power-cycling is another matter entirely.

As unfortuntate as it is not being able to adjust the power-up volume, this case is closed.
Sorry for much ado about nothing.

My best guess about why the Main Volume was getting reset to the default value for the voice is that you may have reselected the voice. For instance, if it was the default Acoustic Grand Piano voice, pressing the Portable Grand button after having changed the functions would have reset them to their default values for that voice.

Note that, on most Yamaha models, not all of the functions in the Functions menu have default values for each preset voice, so some of the functions may keep whatever settings you've changed them to even if you select a different voice. The only way to be sure which functions have default settings for each preset voice is to change all of the functions to new settings, select a different preset voice, and then go through the Function menu to see which functions have been changed from the settings you'd previously chosen.

In fact, different models can vary from each other as far as which functions have default settings for the various preset voices. It seems to be related to what sorts of preset voices are available on the keyboard.

For instance, I've got a few different PSR-E4xx models, and all of them have the ability to layer two different voices together (Main and Dual). However, my YPT-400 (PSR-E403) doesn't reset the various Dual Voice function settings whenever I select a new Main Voice, whereas my other models do reset those function settings. That's because my other models include certain preset voices which are really two voices layered together, so for that to work correctly the keyboard needs to turn the Dual Voice option on or off for each preset voice, as well as setting all of the Dual Voice functions to specific default values. In contrast, the YPT-400 doesn't include any layered voices in its list of preset voices, therefore it has no need to force all of the Dual Voice settings to specific default values each time a different Main Voice is selected.

 

[2fingerchord]

My best guess about why the Main Volume was getting reset to the default value for the voice is that you may have reselected the voice. For instance, if it was the default Acoustic Grand Piano voice, pressing the Portable Grand button after having changed the functions would have reset them to their default values for that voice.

Which is the next point where you're spot on
I had indeed used the 'Portable Grand' button to exit the menu, as there is no good way to exit it (you can only cycle it endlessly with the 'Function' button).
This subjectively did not change the voice (as it had already been on Grand Piano before), but technically it reselected the voice, discarding the value chosen manually in the menu.
Thanks again!