I want to keep a running total of a balance column, so I have a formula
adding the profit and loss of the day, and adding it to the previous days
total. It works, but it starts by filling the whole column with noughts to
the bottom of the page. As I add values, it repeats the latest value all the
way down the page. I want to keep the cells empty until a new amount is added.

I would also like to display negative values in red.

Thanks for help...