OK, I have been having problems setting up playlists, and I think some of the problems (other than my lack of computer skills, hey I am pharmacist, not a computer programmer) is that some of my files where saved on auto, others MTP, and others MSC, so depending on what I set it to, the different software shows different songs available. So I am going to completely start over (I have only added 50-60 songs) and start from scratch. That being said, what mode should I set my fuze in so when I do set up my playlists, I do not have this same problem?
If you are going to manage your files by manually transferring them, most folks prefer MSC, as it’s simplest. MTP mode uses components of Windows Media Player to see the Sansa as a media device rather than a simple flash drive.
MTP handles secure media, with DRM, like subscription services and library audiobooks. Niceties like album art, and song ratings are transferred. But, MTP is a virtual mode supported by WiMP10 and later, so it is a wee bit more complex.
Bob 
