conditional formatting

I'm trying to conditionally format an excel sheet. I have 12 columns and 11 rows; I want each cell to compare to the previous cell in that row. If the value is higher, the font is green; if the value is lower the font is red; and if the value is the same, the font is blue. I can make it work for the first column but if I try to continue it across all columns, it always compares to the original cell in column A. How can I set it up to always compare the cell to the immediate left (e.g. compare cell in Row 1, Column C to cell in Row 1, Column B; then compare cell in Row 1, Column D to cell in Row 1, Column C, etc) ?