Animation playback weirdness

I’m having an issue with my animation playback. I created an animation earlier that involved a cube moving across the screen. I quit that file, but as I try to playback my current animation, which in no way involves a cube, it will play for a second, and then it goes back to my previous cube animation. What is happening here?

I think this is what you are describing:
You render an animation involving a cube
You close the first file and render a second file which does not has a cube.
You play-back the animation and sees the cube at the end.

Is this what you are seeing? My guess is that the saved animation sequence is overlapping. Your second animation is probably shorter than the cube animation, and yet blender uses the same filename to save the video. so in the end, part of the video file is your new animation, part of it is still the old cube animation.

This is a bit difficult to explain, next time, just make sure to save the animation with an unique name.

That should do it! Thank ya kindly, mpan3.