There are 2 ways to edit a draft on Android,
You can edit minimized draft via compose.
- Tap on ‘Compose’ > Select ‘Edit : <draft>’
You can edit the saved draft via the 'Drafts' folder.
- Open 'Drafts' > Tap on the message you want to edit > Tap on the 'Reply Button'.
Note : The minimized drafts will be deleted after your force quit Canary.