Changing names of Pivot Table columns

Hey!

I created a Pivot that will be updated daily (source data changes daily). When I set up the pivot, the name of the columns is like this: "AMS-CNT-Test Instance ID", since I am applying a count of "Test Instance ID". However, for reporting purposes I would like the column to be named simply "AMS" so when doing a chart of this pivot in a Dashboard the name of the series is simply "AMS" and not "AMS-CNT-Test Instance ID".

I did this manually the first day and it worked fine. The following day, since I have set the pivot to update immediately when there is new info in the source sheet, when the pivot updated it did not recognize the columns I had renamed, so it created again the column "AMS-CNT-Test Instance ID" and left blank the column "AMS". Obviously the chart in the dashboard did not display and had the message "source data has been changed". Can I remove the "CNT-Test Instance ID" permanently? It is not a big deal to have it in the pivot I guess, but in the dashboard that naming looks terrible.

Thank you!!!!!