double click to open

My wireless mouse (Apple) and the trackpad are both set to open files when I double click, and ever since I installed the Sierra OS, neither one will open up any files. I have to use the "open" tab if provided, or in Preview, I have to right click or use the icon in the toolbar to open up the files.

Is there a setting to disable or enable somewhere in System Preferences that I'm missing so double-clicking to open files will work again with the mouse or trackpad?

Thanks,

Dani