That question has been answered a bunch of times in this forum. I did it through the Windows 10 Fitbit app for the first time this morning. Best advice I can give you:
1) Click on the little index card looking thing on the tab bar
2) Click on your ionic Watch
3) Click on Media
4) Then choose your Media Type
- Pandora only lets you choose stations (not playlists 
)
- The stations show up on the Pandora App several swipes in (not under the music app on the first swipe: also )
- Deezer seems popular, but I've never heard of it. There is a Deezer app that I can't uninstall.
- Personal Music found all my iTunes playlists.
5) All music seems to update only when the Ionic is being charged. Probably not a problem if you charge the watch on your home wifi network, but I'm not sure what happens the rest of the time. That will be something to stay tuned for.
Good luck.
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