It's possible, if an iPhone setting is set wrong, for you to see and the iPhone to play unwanted music, music that's in iCloud but which you never specifically synced to your iPhone. Here's how to manage the appropriate setting for iCloud music.
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Recently, one of our TMO editors was outdoors, listening to music on an iPhone, and, suddenly, Christmas music started playing. That was unexpected, annoying and a mystery because there were only two playlists on that iPhone, and neither contained Christmas music. Ack!
The mystery is explained by the following setting: Settings > iTunes & App Store > Music.
What that setting does, when ON (as the annotation says), is to "Show all store purchases... even if they have not been downloaded to the iPhone." What that text doesn't say is that the iPhone will also Play those songs when they're next up in the queue and you're in the All Songs mode.
Because our editor had previously bought some Christmas music, and that setting was set to ON, and the music player was in All Songs mode, these holiday songs got mixed in with the other music from the playlists. And so Christmas music (plus some other purchased music) played along with the playlist songs when in the All Songs mode.
All songs mode.
Discussion
1. If you only want music you've downloaded to the iPhone to play, turn that setting to OFF. Or stay within specific playlists and out of the All Songs mode.
2. Similarly, if you only want videos you've downloaded to the iPhone to play, turn the corresponding setting below to OFF.
3. If you don't have a network connection, of course, the iPhone can't access iCloud, show and play these purchased items. If you do have a network connection, if you go out of signal range, you may have some unexpected silence between selections that reside on the iPhone.
4. It might be a bit wordy, but that annotation should also explain that these items in iCloud will not only Show but also Play if queued up.
Where this gets interesting is that our editor wanted to be able to see, when in a local music store, what was in the iCloud purchase list, but because the annotation said Show, it was unexpected that they would actually Play.
A potential use for this feature is an iPhone with a low capacity memory (say, 8 GB) or one that's heavily loaded with apps and doesn't have much room for a lot of music. Being able to see and play all purchased music in iCloud, music that was never formally synced to the iPhone, provides a richer selection of music.
This setting is an all or nothing affair. That is, you can't control which songs in iCloud will be displayed, and it defeats the purpose of creating playlists and then merging them into All Songs. Of course, as mentioned above, you can leave the setting ON for access to iCloud, but remain in specific playlists if you don't want those iCloud songs to actually get mixed in.