[O] where Babel looks for binaries?

[Steven Arntson]

I'm using org-babel to enter lilypond code for music typesetting. I had
an old version of lilypond from the Ubuntu repos installed in
/usr/bin. This worked, but the version was getting old. I installed the
latest stable version from the lilypond.org website, and it ended up in
/usr/local. I removed (apt-get remove) the repo version. Now when I do
ly-tangle, I get:

ly-compile-lilyfile: Searching for program: no such file or directory,
/usr/bin/lilypond

I tried to "customize-variable" on "ly-compile-lilyfile" but there's no match.

How do I change where org looks for this program?

Thank you!
Steven Arntson