What is the MP3 Player Activity and How do I Modify it?
If you are using a basic Unity Program, you will find a MP-3 Player activity 
already programmed in the activity row.
Once you select the MP-3 Activity, you will see the MP3 activity row appear:
If you choose to, you can modify this activity row to play a specific tool, such as a playlist. Here is a list of MP3 tools you can choose from, some of which are already pre-programmed in the activity:
MP3-PLAY DRIVE
Allows you to select either the USB flash drive or the SD card to listen to when both devices are plugged into your communication aid.
MP3-PLAY FILE
Allows you store a link to one song under a key or sequence.
MP3-PLAY PLAYLIST
Allows you store a link to an entire playlist under a key or sequence.
For example, you might have a song you are really crazy about at the moment. You could store the PLAY FILE tool, select the song you want to link to, and then activate the key or sequence you used on your overlay to hear the song as often as you wanted.
MP3-PLAY-PAUSE
This tool allows you to pause a song, then go back to it.
MP3-PLAY PLAYLIST
Use this tool to store one playlist under a key or sequence on your overlay.
MP3 PLAYER MENU
This tool puts the link to the MP3 player menu on your overlay for easy access.
MP3-PREV
Select Previous to listen to the song before the one currently playing.
MP3-STOP
Select this to stop listening to music.
Storing a MP3 commands in your Activity Row:
1. Open the MP3 Activity (see picture above)
2. Select the Set-Up Key (the right key on the top of the VT/VG case) You will see "Select the key you wish to modify" appear in the text bar at the top of your screen.
3. Select the key on your overlay you want to modify. If there is not a blank key in your activity row, select an already programmed key, then select ADD A ROW in your Modifying Screen.
4. Select SPELL MESSAGE OR DEFINE KEY FUNCTION.
5. You may keep any spelled message you already have or Select “Clear display” to not have any text appear with the key.
6. Select INSERT TOOL. 
7. Select the tool you would like to use.
8. If you selected MP3-Play-Playlist you must now follow your directory to find the playlist you wish to play.
9. Your top line should read something similar to <MP3-PLAY-PLAYLIST>(USB Storageplaylist.m3u) if you chose to play a playlist. This is just an example if your files are stored on your USB Flash Drive. You must know where you stored your playlist in order to link it properly. If you chose a different tool you may just see the name of the tool in <>.
10. Select OK.
11. Change the icon and label if needed
12. Select OK when you are finished.