Firefox Automatically Download Prevention

I think that I have accidentally got it so that instead of opening a file when a link is clicked on, it downloads it to my default location - must have clicked the tickbox by accident. Doeas anyone know how to revert this back so that files are opened as opposed to saved by default?

Tools > options > content > filetypes > manage should be pretty simple from there onward.

Thanks - I just KNEW it I'd seen it somewhere before, but i must have skimmed over that dialogue box.

Cheers