When downloading a file, I use to get a pop-up box that asked me if i wanted to open it or save it, and there was a box that said "don't ask me this again. I accidentally checked that box. Now every time I click on a file it asks me where I want to save it but it won't let me open it to view it first. How do get it back to the way it was?

I have tried changing my download options, I've tried re-setting the browser options. Nothing works. There has to be a way to get back to where is asks "where would you like to save" AND gives me the option to click a radial button to Open the file and view it before saving it.