NOTE: the costumes of the sprite where not edited at all. this is real. WHAT I FOUND: what i did is i made a new project from scratch, went into the custume section of the starting sprite(the sprite you get when u create a new project), deleted costume2, went to get a new costume from the custom costume library, and selected cat1-a. then i switched the the costumes back and forth,(switching the current costume from costume1 to cat1-a and back repeatedly) and found that the sprite seemed to be moving slightly. heres why. if you know the basics of scratch, you will know that the center of each costume for a sprite is based off of where the crosshair in the costume editor is on the sprite(though the sprite can overlap the crosshair, hiding it from view, and its also very hard to see it without zooming in). and i did not add any scripts telling the sprite the move, so this only can mean one thing: one of the two costumes is slightly dispositioned on the crosshair! i have a script in this program that shows the sprite switching costumes back and forth every 1 second, to show you.
read in the instructions! read the whole thing to understand!