I used CTRL-X to cut chords that I wanted to paste elsewhere, but BiaB zoomed in when I did that for some reason. Now I can't figure out how to zoom out. I did a search, but none of the "solutions" I found actually worked -- "CTRL-Num Pad-minus sign" did nothing, nor did using the scroll wheel while hovering over anything.

What version of BIAB and what version of Windows do you have?

Are you running dual monitors?

I've just tried CRL+X and it did nothing on my chordsheet in BIAB 2018. I have a single monitor.

It sounds like it might be more of a Windows problem than a BIAB problem. One way that you should be able to check this is to go to "Options" and select "Return to factory settings".

Is this a Mac or PC?

Right-click on any chord cell, select Display Options, check / adjust these settings: