Q: itunes command-L shows current song and selects entire library

Hello jjnorris,

Thanks for that info. I know that having the Command-L keyboard shortcut not work in iTunes is not the Apple experience you expect. Command-L should show the currently playing song in the list according to Keyboard shortcuts - iTunes Help website.

After testing, I was not able to replicate your specific issue in the same version as yours. The next step would be to re-install iTunes to narrow this down: OS X Yosemite: Reinstall apps that came with your Mac

Thank you for using the Apple Support Communities.

Thanks for that follow up. Have you tested this in a different user on the same Mac yet? This can narrow down a system wide issue or if this is in a specific setting in a user account. Please check this article on the steps to test in a new user. 

How to test an issue in another user account on your Mac - Apple Support