Change year in many date fields in excel?

If the date cells are all in one column, here's a quick and dirty way:

Assuming the dates are in A1 downwards, insert two columns to the right.

In B1, put the formula: =DATE(YEAR(A1)-4,MONTH(A1), DAY(A1))

Copy this formula down the column to recalculate all the dates from column A.

Now select and 'copy' column B (the new dates) and use 'paste as values/paste values' into column C.

Now delete the original column and the one containing the formulas to leave the new fixed dates.

If the original dates are not in neat columns you may have to do a bit more work!

1. Highlight the column where the dates are, then under the Home Tab, go to "Find & Select", then click "Replace"
2. Type "2014" under Find What, then type "2010" under Replace With
3. Click Replace All