How do I get rid of too many active cells in Excel

[Josey]

I have clicked on a cell location and a box appeared; It should disappear
when I clicked on a new cell location but did not. I fixed the problem by
closing the file and reopen it. But what causes it? I have a romote mouse.

 

[NHarkawat]

Probably the control key on the keyboard is pressed that causes you to
select multiple cells

I have clicked on a cell location and a box appeared; It should disappear
when I clicked on a new cell location but did not. I fixed the problem by
closing the file and reopen it. But what causes it? I have a romote

mouse.