itunes not showing as a choice for default app for videos

I want iTunes to be the default player for videos, especially the mp4 files. I went to change it to iTunes in the default apps but iTunes is not one of the choices. To look for something not showing it sends me to the Microsoft Store where I search for iTunes but the only choice it gives me is to OPEN it as it is already on my computer. The setting in iTunes is to always warn me if it is not the default player for audio files but I could not find the setting to ask about video files. There is no message that I need any update. What can I do to make iTunes the default player for mp4's when it will not give me iTunes as a choice in the list?