Edit: There's now a way to change the licenses for all of your audio (which I did). Though take care as a few pieces have some copyrighted material in them which should be specified next to the license.
Ignore all the license texts on my songs that were posted before today - September 19th, 2015, except for those that say "This work may not be used by anyone." as they contain material that I don't own. Every other song is under CC. If a description of a song and the license after today - September 19th, 2015 - says otherwise, refer to the current song's license as this text post only permits the use of all older uploads (with a few exceptions mentioned above).
I would change the licenses on them if NG had a bulk edit mode.