How can I go back and add to existing frames? e.g. add detail

Im trying to add more detail to my frames and not succeeding. whenever I click with brush it just changes the colour of the what is underneath. how do I do this?

@Blastercastgirl Hi. Can you provide a bit more details? Are you using a bitmap layer or a vector layer?

When you say you’re adding more details, do you mean trying to draw on previous “drawings” that are on different frames?

If possible please show a screenshot of the problem.