One way:

Tools/Options/Calculation, check the 1904 Date system checkbox.

(the 1900 date system can't show negative times without using additional
functions). Format time as desired.

In article ,
"Jason" wrote:

I need to subtract one Minute from the value of another cell, sometime the
value will be greater than one minute sometimes less. What I would like it
that if value of the cell is greater than one minute I would like the result
to appear as a red negitive number, i.e. (0:00:19) Any sugestion on how I can
do this. All I get now is a error.