Cell Range References (Labels / Names)

I inherited a Profit & Loss (P&L) template from a colleague. She developed it on Excel 2013 and I'm on Excel 2010, but it's not clear that is the issue here (tho, never say never).

The spreadsheet was set up for quarters and I've expanded it (by copy and paste) to 12 months. It has the typical tables: sales revenues, cost of goods, admin exp, etc. Each table has a number (varies from table to table) of rows with a subtotal in the bottom row of each table. There is also a label row above all the tables (this now has the month labels).

The problem: The subtotal (bottom) row of a table uses the formula "=SUBTOTAL (109, ref1)". In the original spreadsheet, ref1= "QTR1" (or QTR2, QTR3, etc.). I'd like to change that to be MONTH1, MONTH2.... However, when I enter MONTH1 or MONTH2, etc. for ref1, I get a formula error. Which I suspect is expected.

What I noticed is that if I highlight ref1 in the subtotal cell formula and then select the cells I want included in the subtotal, the first selected cell shows a "B8". With 2 cells, it shows "B8:B9". Good so far. However, when I get to the last cell before the subtotal row, ref1 changes to "[QTR1]", so the final subtotal formula shows "=SUBTOTAL (109, [QTR1])".

I've tried to change QTR1 to MONTH1, but get an error. I used Name Manager, but QTR1 doesn't show up on the list (However, the tables are named and seem to reference the columns correctly). If I do a "Define Name", the window pops up w/the name entry empty and the "Refers To" containing "=tblName[QTR1]" (tblName is the name given to the specific table (revenue, cost of goods, etc.) and does show up under Name Manager).

I tried an experiment and in the revenue table I deleted (move left) the cells (up to but not including the subtotal cell) under MONTH1, and then inserted (move right) a new set of cells. Now the "Refers To" shows "=tblSalesRevenue[Column7]".

So, apparently, Excel can assign some kind of label to a set of cells. My question is, how do I (if I can) change that label, or name, so that the column of cells I want to use for my subtotal formula will work (MONTH1, MONTH2, etc.). It's not clear that Define Name or Name Manager is what I should use. I looked at the original spreadsheet and there are no Name Manager listings for QTR1, QTR2, etc.

Additional Note: I forgot to mention that this isn't a show stopper, just a nuisance. If I use normal cell references (i.e. B8:B11, etc.) the spreadsheet works fine and as expected. This is just one of those "nits" that I'd like to understand so that I can make the spreadsheet programming more "readable".