Can’t make it my default

I am not sure if I am understanding this app correctly. When I change it to my default viewer everything locks up. The spinning wheel, and in order to go further I have to force quit. I don’t know if I am doing something incorrectly, if I am then I would give it more stars, but for now since I can’t use it as the default browser as advertised I don’t find it that great.

Tmogie about Image Viewer