How can I change the program associated with a type fo file?

I’m having issue with getting a computer at work to open up jpegs. The problem is that all jpegs and many other media types for that matter are associated with this Intervideo Home theater. so much so that they all share the same logo and under file properties they are listed as being an Intervideo media file. I have tried importing them from a usb drive, tried saving them with .jpeg in the file name. I’ve changed what program jpegs open with to paint using the properties menu. Nothing seems to work. We don’t have IT at work and the program came installed. I’m probably just going to get permission to uninstall it. I have tried to change the settings under “set program access and defualts” menu, but the program overrides this and always sets itself to the default. There is also no option in the program as to what file types it is associated with. Any help would be appreciated, thanks.