Slideshow Audio lost

I am a long term user of FotoMagico from version3. I am now using Yosemite 10.10.3 with FotoMagico 4.5.5 for some time without any problems. I have just lost the audio on all slideshows - with audio output at maximum values, the sound is just barely audible. Audio for iTunes and other programs is normal. I have another iMac with Yosemite 10.10.3 and some slideshows installed on FotoMagico 4.5.5 where sound is quite normal and the comparative settings for FotoMagico and System Preferences for Sound are the same on both machines. I would welcome assistance.

Error was that somehow, and inadvertently, the Master Volume control had been set to minimum level and it had escaped my notice. Volume adjusted and now all slideshows have normal audio output again. Perhaps an accidental keystroke was the cause ?? No further assistance required.