Let’s say you’ve nearly completely an animation but then decide you want to change some aspect of the character’s appearance… for example, longer torso, longer forearms, etc. This could be a very problematic and time consuming situation to deal with. Luckily Spriter Pro offers a feature to help make changing individual aspects of any given object easy.
Copying Individual Attributes of an Object to All Frames

Spriter Pro User’s Manual version 1.4

For this example, We’ll be taking the free example Spriter file called “Grey Guy” and changing the forearm images and bones in the idle animation to give him very long forearms.
Here’s how.
1) Load up the Spriter file in Spriter and click on the Idle animation so we can start editing on the fist keyframe at zero seconds in the timeline.
4) Once both forearm images are their new scale and saved over the originals, go back into Spriter and click the reload images button near the top right of the “files palette”. You’ll see the new forearm images, but they will now look too long.
2) Select each forearm bone and stretch the forearm until the new length is to your liking. Now click the forearm images and remember the number in the x scale attribute in the properties palette for each of them, as you’ll need this later. note: In this case we need to be very exact because we’ll be editing the image files to match the new scale. but if this is not needed, you don’t need to use the numerical settings in the objects properties palette.
3) If you don’t want the forearm images to be stretched to match the new size, and you want them to actually be  the new size, then, using your graphics program of choice, find the forearm images that are being used in the arms folder of the Spriter project, and scale them to the same percentile and in the same direction that you did in Spriter in step 2. For example, if the new scale of the forearm image in Spriter is 1.47, that means its 147 percent of the original size.
5) Now just select each forearm image ans switch their x-scale to 1 in the properties palette.
6) Now your changes look correct, BUT are only effecting the first keyframe at zero in the timeline. If you scrub to other key frames you’ll see things are a bit messed up. Don’t worry… here’s comes the part were we copy the new properties to all key frames.  Go back to the very beginning of the timeline (the very first key frame that has your proper changes.) Select each forearm BONE by left clicking it, then hold the right mouse button on a blank part of the canvas and select “Copy Selected Item Property to All Frames/ x scale”. Then do the same thing for each forearm image.
7) We’re not quite done yet. Because each forearm bone also effects the child bones (hands) and therefore the hand images indirectly, we must do the same for the hand bones. Select them at zero in the timeline, one at a time, and choose the same option via holding the right mouse button on a blank part of the canvas and selecting “Copy Selected Item Property to All Frames/ x scale”
Once you finish this, if you play the animation you should see the new gibbon-like forearms are correct throughout the animation. NOTE: For this example, we almost could have multi-selected the forearm bones, hand bones, and forearm images once the first keyframe was perfect and then right clicked on a blank part of the canvas and selected “Copy Selected Items to All Frames”, because they don’t change any other attributes throughout this specific animation.  BUT, for animations where the forearms change angle or scale or image being used throughout the animation, we would have lost those changes in the respective keyframes.