Hi Bernd,
Thanks for highlighting this to me. I've figured out the issue of the shifting of the notes. It was down to an incorrect measurement of the song width versus the highlighter image width. You would find that the highlighter editor would have incorrectly let you draw beyond the left/right of the songview. I've fixed this for beta 10 and attached screenshots of it working (assuming the group allows it - could be a restriction on file sizes for attachments).
The song notes aren't saved with the song file, instead they are saved in the OpenSong/Highlighter/ folder. When a song is loaded, the app looks in this folder for a file that matches the current song (and screen orientation). E.g a song located at OpenSong/Songs/test song will potentially have a matching highlighter file at OpenSong/Highlighter/MAIN_test song_p.png for a portrait note. Landscape files end with _l.png
If the matching file/orientation highlighter file isn't found, nothing should appear on the screen, or when you try to edit the highlighter note.
I wonder if there was an error loading the highlighter file (due to the wrong size) that was causing it not to be displayed. Can you test beta 10 when I release it please. You may have to delete the original highlighter file if it is still there as it will be the wrong size.
I likely won't release this to Google Play until Monday. Whenever possible I don't push updates at the weekend as this is when people rely on the app working. I only do this if there is a major issue that has been identified. I will, likely, put the file into the downloads folder later today though for manual testing if you are keen!
Gareth