Yes, you can edit a draft:

iOS

1. Select the draft you wish to edit.

2. Select the pen and paper icon for the section you wish to edit.

3. Make edits (either full edits or placeholder edits).

4. Click 'Done' to save your changes. 

Browser 

1. Select the draft you wish to edit.

2. Hover your mouse over the section you wish to edit.

3. Click the 'Edit' button that appears.

4. Make edits.

5. Click 'Save' to save your changes.