Selecting "print" in Outlook on Firefox causes "save file" to open up; doesn't do this on Internet Explorer & didn't use to on Firefox - why now & how to fix it

While on Firefox and in Outlook email, when I select print, instead of printing, a dialog box appears asking me to save the file. It never has done this before. I tried printing several emails & it went to "save file" every time. So, I tried saving the file. When I then pulled up the save file, it would not let me "open" the file to then try and "print" it - it only asked me to "save" it again. I, then, exited Firefox and opened up Internet Explorer and went into Outlook to try and print my emails there and it let me print my emails. I, then, updated Firefox (which I needed to do) and tried printing my Outlook emails while in Firefox; but, I still got the same "no print"/"save file" response that was troubling me before the update. Help me, please.