ex flash user issues

Since I used to work in Adobe Fash earlier, there are some things i would like to know how to make in Animate.
So, how can I (in Animate Pro) change symbol properties in one layer ? In Flash I have managing it on keyframes with changing options “single frame”, “play once” and “loop”, and still did not figure out how to do the same operation in Animate Pro.
Next, (this got nothing to do with Flash) every time I want to vectorize images and apply optical registration, I got message “optical registration failed”. So can someone explain me from the very first step (say scan settings) how can I properly vectorize images with optical registration, or post a link to some tutorial that solves my problem, because sometimes I work on classical hand drawn animation?