Centering Column Title in Pivot Table

Hi All -

I have a pivot table with two column values. One value is Period (basically stating which month the data applies to) and then the data column header itself (in this example Hires, Terms, Transfers). I would like to center the Period column header over the actual data values, however, whenever I try to marge and center the title the pivot only changes the data column header itself, instead of the Period/Month header.

Here is what I currently have:

Pivot Header example 1.PNG

Pivot header example 2.PNG

Here is what I am trying to achieve:

Pivot header example 3.PNG

Thanks for the help in advance