How do I add a note to a recording?

Open the recording from the Logbook, and you'll see Replay, Compare, AR and three dots for more actions. Tap on the dots, then tap on Add Note. Once you've added your note, tap on Save in the top right to save and exit.

If you want to edit the note later, tap on the three dots again → Edit Note. Otherwise, you can just tap on the note itself which will open the editor.