Im trying to start animating on Krita, and learned about the timeline,onion skin, and animation dockers. When i draw on one frame and go to the other, the last frames does not change color (red for previous frame) or opacity it stays the same. But onion skin works when i click on a frame because that frame changed opacity and color(green for current/next frame). I need onion skins to know which frame im on.

This post may be of use or helpful to you: viewtopic.php?f=139&t=152998

As ususal, a .png screenshot showing the problem would be helpful if you can do that.

You don't need onion skins to know which frame you're on because the timeline shows that with the orange frame highlight. The onion skins show you what the previous and next frames content is.