Help!  I am a novice trying to modify a worksheet that someone else
created.  I am baffled by something that I can only describe as a
"floating" cell.  Essentially, it is a cell that has several different
assigned values that change when it is clicked.  For instance, "1"
appears first.  Then when it is clicked, "2" appears. The when it is
clicked again, "3" appears.  And then when it is clicked again, "1"
appears again.  I try to delete this cell, but I can't.  The reason
that I say that it is "floating" is that it covers up the cells below
it, and isn't influenced by the cells below it.  For example, I can
fill the entire worksheet with black cells, but this "floating" cell
isn't filled with black.

What is this this function called? And how do I turn it off?

Thanks for your help.