The eggs should stay relatively upright but sometimes an egg will turn slightly as it grows and the gecko forms inside of it. This should not be an extreme amount--just a little to one side or the other. I usually leave my eggs be once I have placed them in the incubator, so if they do roll slightly they stay that way until they hatch, but that doesn't really usually happen very often. I would suggest burying your eggs a bit deeper in the substrate if they are rolling around too much.