I use the “unfold to one big chorus” every time I do a new song. It would be great to have a button to do it. Or at least a keyboard shortcut that I can remember.

Under options/arrangements you can set your initial settings to any number of measures and choruses. This is a global option so all songs will open with this setting. My music computer always opens with 64 measures and 1 chorus.

What version of BIAB are you using? Recent versions have this settable as a default as Mario said.

That's why I made a one button click to do that
BB-Quick-Menu-&-Mixer-8.zip

That’s not really the solution I’m looking for.
I’m mostly a blues player. So most of my songs are either 12 or 8 measures. I enter the chords in the 12 bars and usually do something midi (a different bass line or horn parts etc.) over the 12 bars then unfold and make changes or adjustments over the entire song. It’s that big a deal but it is three folders deep.

I’m using Mac 2023. Your app/macro doesn’t work on Mac. Ami right?

It sounds like the 1st & 2nd endings feature will do what you're looking for.

Have a look at https://www.hammerspoon.org/
https://www.hammerspoon.org/go/

https://www.hammerspoon.org/docs/hs.application.html#selectMenuItem

https://stackoverflow.com/questions/68146683/selecting-a-menu-item-with-hammerspoon

GUI for Hammerspoon
https://github.com/asmagill/hs._asm.guitk

I can see the usefulness of the request by Blues1952, since he doesn't want to set a default because each song may be different. I wonder, if there was a hotkey (instead of a button) for Edit, Song Form, Unfold, would that help?

Actually if you are on the Mac you can set menu items to any hotkey you like.
https://www.macinstruct.com/tutorials/create-a-keyboard-shortcut-for-any-menu-item/

I posted so many things I forget I posted them:
Mac Custom Keyboard Shortcuts