Audacious

First place where to ask that question would be the distro developer's community. It's the developers of the distribution's packages that may decide which packages replace/uninstall other packages. They can tell you the reason, if any. It sounds odd.

Alternatively, fetch the packages from the install media or remote repositories and examine them. You may also take a look at the package sources and figure out why they replace packages like that.

Afterall, it's a distro for learners. ;-)

Given he said he installed MuseScore from a PPA (a type of third-party package repository), contacting the distribution folks may not do any good. I would recommend disabling any and all third-party software sources and then reinstalling UberStudent's "official" packages for both Musescore and Audacious--which are most likely exactly the same as the Ubuntu versions.

For a third-party repo, the "distributor" is the maker of that repo, of course. That is, the people to contact/ask are those, who have created the offending packages that uninstall/replace other packages. The OP didn't tell what PPA it is and which installation targets it is made for.