Stop Cut And Paste From Wrecking My Array Formulas

I have a worksheet "Expenses" with columns Month, Category, Expense, Amount. There are four categories and, obviously, 12 months.

In the workbook is another worksheet, "Totals" which lists the months across the top, and the categories down the left. Then I have array formulas in each cell, that look like this:

=SUM(IF(Expenses!$B$2:$B$990="July",IF(Expenses!$C$2:$C$990="Acquisition",Expenses!$E$2:$E$990,0),0) )

This works fine, until people start moving cells around in the Expenses sheet. Say they sort everything they've put in by month, and then they want to move July up to the top because it's the start of our fiscal year. So say they have six expenses for July and they cut and insert them in at B2. Suddenly the formula now says:

=SUM(IF(Expenses!$B$8:$B$990="July",IF(Expenses!$C$8:$C$990="Acquisition",Expenses!$E$8:$E$990,0),0) )

I thought by using absolute cell references instead of relative ones, I could avoid this problem, but that's apparently not the case. I tried changing the cell references in the formulas to relative ones but it still happens then too.