You are confused because the buttons have several purposes. The +/- are volume up and down and Next/Previous. If you press and hold the button, you control the volume. Quickly press and release for Next or Previous. The button below them is Pause/Play and Power (again press and hold to power on or off). The switches on the left side are Hold (no buttons work) and Random (play loaded songs in a randomized order)
For the hold feature, move the switch to the padlock. Unlock by sliding the other way. The Random switch has a more obvious label - Random or Normal.
The user's manual for the MP-C582 is available here: http://www.cobyusa.com/files/manuals/MPC582_MN.pdf
. If the direct link doesn't work, try the support site: http://www.cobyusa.com/?p=doc
and search for the model (MP3 & Portable, MP3&MP4 Players, MPC582.)
I hope this helps.