Cameras don't shift randomly. You have changed some keyframes or invoked the camera tools on your parented camera. Without seeing the specific setup, this is impossible to figure out, but you did something. Similarly, if text layers are involved with text animators, the text animators may actually change the position of the text. And finalyl, if there are layer styles somewhere, they would break 3D rendering, which could also appear as if the stuff shifted places because suddenly the Z position is no longer properly calculated...
Some things to consider:
• If you have multiple keyframes selected and move the camera, you will adjust values for ALL the keyframes selected. Note that, if you click on the name of the parameter in the left column of the timeline, all keyframes for that parameter are selected.
• Are you seeing non-linear spatial interpolation? You can't see spatial interpolation on the timeline, only in the preview window, and for cameras only when you are using a view that shows the camera. Use Animation/Keyframe Interpolation to determine whether your keyframes are being eased through space as well as time. You can set the default interpolation of keyframes to Linear in AE Preferences.
You need to understand something ABSOLUTELY CRUCIAL to AE Wisdom: it's not the kind of application you use for a couple of tricks and expect things to turn out right the first time. It takes a good knowledge of the AE basics to make it do what you want. If you blow off the basics, you face countless unproductive hours of frustration.
So how do you get the basics? You go here:
If you follow the link above you'd probably stumble across what may be the best FREE training in AE Basics, compiled by Adobe's own Todd Kopriva:
Read all the glowing things Todd writes about this series of tutorials.
Well, that ought to get you started on shat many people consider a journey rather than a destination: true Affer Effects Enlightenment.