The sound volume keeps changing itself

Yeah, that's the problem right there. I have tried using both a sound card and the onboard sound, always the same problem. It isn't the speekers since it's the same on another pair of speakers aswell as the ones I use right now.
Can it be a software problem? Most often after It has been on for awhile, regardless of the volume I have put it on, it settles on a setting that is a little to low and if I decide to change the volume again it starts freaking out.

Install Lunix, problem solved.

Or give us more details: your OS, your sound card, what you mean by "freaking out"