Many, many thanks to the developer. I checked the application thoroughly and everything is working perfectly. Now it is possible to back up to the same location, the application remembers the path to the backup location, font changes are saved, if you select text you can get information about it and the developer sorted the problem of speed, as I've suggested to him below, by making the application store each note in a separate file in the user library. However, there is still room for improvements:

1. Doesn't support copy/paste style.

2. No spell check.

3. Doesn't use the system colour palettes.

4. Can't make links.

5. Can't make lists (numbered or bulleted).