Water dancing speakers from Spencer's. Help?

So for christmas i got these water dancing speakers from Spencers and i love them and think they are cool. Although recently when i play music on them with my iPod i'll turn up the volume to a happy medium loudness where they are loud but not to loud. So when i do that i'll set my ipod down then look away and i can hear that my speakers are getting louder, so when i look back my little volume bar is all the way up and bot where i left it at. So i turned it back down to where it was before and watched and waited. Sure enough the volume scooted right back up. It was almost like someone was pressing the volume buttons on the side of the ipod, but no volume sign was shown on the ipod screen.

Im very confused as to why it is doing this? It gets really annoying because its too loud. Is there something wrong with it? Is their specific thing im suppose to do witb these speakers?

Please reply with a legit answer. I need to know if i need to take these back and get new ones. Thank you!