excell

John1944 

You did not mention which column currently contains your (transaction) amounts. I will assume they are in column C, and that row 1 contains column headings.

Start by inserting two columns to the right of column C. (Of course, that's not necessary if column C is the last-used column.)  Then, into cell D2 place this formula:

=IF(C2 < 0, "", C2)

and into cell E2 place this formula:

=IF(C2 < 0, C2, "")

(Or swap those two formulas if you want negative values in column D.)

Copy those formulas to rows below, at least as far down as needed for your data.

Because formulas determine values (but not formatting), format the newly-populated cells as you desire (for example, as Currency).

Now that everything (presumably) looks right, select all the newly-populated cells and copy them. Without changing the selection, paste their values into those same cells (thereby replacing the formulas); you can (probably) do that by right-clicking any of the selected cells and choosing Paste Values from the popup menu that appears:

(You can alternatively do that pasting from the Paste Special dialog.)

Do things still look right? Examine some newly-populated cells.  Do they now contain values (rather than formulas)?  Is column C now useless?  If so, you can delete column C.