OnSong uses the name of the file as the song title when importing files that are not text-based. This means that your PDF or word processing files will appear as the file name, omitting the file extension. If you want to rename the song, you can use the Song Editor to change or modify the metadata information about the song.
To do this, open the Song Editor by tapping the Attachments Menu icon in the Menubar and selecting "Edit Chords and Lyrics", or in OnSong 2020 tap on the text cursor icon to open the Song Editor. You can then tap on the "info" icon in the Editor Menubar to open the Metadata Editor Menu. From here you can change the title, artist, key and other information. When you tap to close the menu, the metadata in the song editor is updated. You can then tap Done, or the checkmark to save change and update the song title.