<p>
I too would like to see separate default themes for songs, bible verses and custom slides, and an option to override this when creating the custom slide or after searching for Bible verses prior to going live or adding to the OOS.
</p>
<p>
In the meanwhile however a workaround of sorts:
</p>
<p>
It is possible to have separate themes for songs and Bible verses by going through each song and giving it a specific theme. Then in Options->Settings changing the Default theme to the one you want for say Bible verses, and checking the "Use song themes" option.
</p>
<p>
However I decided going through all my songs and setting the theme would take a lifetime, so I've written a script which will mass update the theme for all songs, or optionally all songs that have no theme or have a specific theme.
</p>
<p>
Find it at the bottom of: http://ricepudd.googlepages.com/myopenlputilities#theme
</p>