It's possible to edit in the desktop app but not in the mobile. Also please can you make the mobile comments Copy& Paste-able. Sometimes I want to copy whats been written by me/coach to somewhere else and I can't do that from my phone (I only log in to desktop app if I really need to do this on a big chunk of text)

Agree, I cannot believe it still hasn't been done

The web app allows editing comments. When I realize that I want to add more information to the same comment or fix a mistake, I have to go to a desktop web browser to make that change. It would be great to be able to edit this from the mobile app.

This is specifically on the mobile app. On the phone, it doesn't appear that there's a way to edit my post-activity comments. I can delete them but I can't tap on the post activity comment box to edit my text. It does work on the web though.

If you entered the comments, just click back in the same box the comment is in. It will let you add or delete whatever you need.