Sum Function Has Changed into Showing Average or Median

Suddenly Excel no longer sums numbers in highlighted cells for us but rather shows averages or medians. Any ideas as to how to return to the original functionality (preferably without reinstalling program)?

Originally Posted by protonLeah

I have XL'7, but, try right clicking the average/median and see if you get a pop-up menu of options.

Wow, that's great! It did the trick. Thank you so much!