Help with Photoshop editing in Animate

Hi, I'm a new animation student who is using Adobe software for the first time.  I've imported my photoshop file into Animate as key frames, that I should be able to edit.  I can adjust the drawings but I can't edit them as it just deselects the frame that I am on.  I am trying to erase some of the drawing so that it fits in with my background.

Any suggestions and advice would be gratefully received as my tutor is unable to help.

Thank you.