Each time OpenSongApp opens up, it rebuilds your song database. This database is used to generate the left hand song menu and the 'Search' feature. When you first open the app, you will be told that OpenSongApp is building your song database. Please avoid searching until this step is completed (you are told when the song database has been built). If you try to access the search feature before the database has been built, you will be told that there was an error. If the database fails to build correctly, you can only search for songs using the file names, so it is worthwhile allowing the database to build correctly.
If there is an error building your database (usually if another app is accessing your storage, or if there is another error such as a badly formatted song), you can force the app to rebuild the search database or the left hand song menu. These options are found in the right hand 'Storage' options menu.
If the app still fails to build the database correctly, you can view the current database log from the same menu. Each time a song is successfully added, it appears at the bottom of the log. The last song to appear before a failed database build indicates that the next alphabetically occuring song is causing a problem. You can manually edit this song file to rectify any issues (or delete it). Restarting the app will also cause the database to be rebuilt.
You can also choose to export a text list of your entire database (for sharing with others) by clicking on the 'Export list of songs' button. You will be asked which folders you want to scan and how you want to share the list of songs.
Note that this doesn't export the songs, just a text list of what you have.