I've only ever used themes set either globally or per song. But recently someone at church used the service manager to set a unique theme for a carol service. Later, after loading a new service plan, that theme for the carol service appeared as effectively the global default theme for all subsequent services which are loaded, regardless of whether saved service plans had a service level theme saved with them or not. No matter what previously saved service plan I loaded, they all came up with the theme used at the carol service as the new global default. I got around it eventually by setting the theme for each song at song level. This was effective since the settings were set so that song level overrode service and global theme settings.
My understanding or expectation is that the service manager choice of theme should only remain active for the particular service that it is selected for. That is, if a different service is selected (a new one is saved or an old one is loaded) the service manager should 'automatically' deselect the service manager theme, so that it would return to the global default or song level theme, not the service level theme that was selected for a previous service plan remaining active as the new effective default theme, overridding the global theme. If the last service level theme is still active for all later service plans, even previously saved ones, it is effectively a global theme, which causes lots of confusion, like we had yesterday morning.
If no service plan theme has been saved with an old service plan, I would expect no service level theme to be active in the service manager, and for the global theme and/or song level theme to operate instead.
I mention this in case others might get confused like I did. Now I know the quirk of the program, I know how to workaround it, by deselecting any theme in the service manager, to allow the global theme to work. (Or, to set the settings so that the global theme overrides song and service level themes, but that is more restrictive.)
But again, the program is a real blessing. Thank you for all who work on it.