Once could open in iMac and it played nice with Webcam

I’ve written Logitech and now trying to get support from Webcam Settings. My app won’t open. It was what I used to make the HD PRO Webcam C920 work (like actually have adjustments). Now this camera only is a pointer and works (but no controls or panels) because Webcam Settings will not open. I have version 2.3 and there looks like there’s an update but since I cannot open, I cannot get it. Please suggest what I might do because I already have iSight. I wanted better, clearer, options with my Logitech and Webcam Settings used to make that possible. Just want access to the panels again. The rating is based on the fact I cannot even open it.

Ofcourseware about Webcam Settings, v2.3