Changing the Date Format for GROUPED dates in a PIVOT TABLE

I was having the same problem. What I have done was to right-click on a value for which I want to change the view on the pivot table and selecting "Ungroup" option. This brings back the reguler view format. I hope this can help you.

As of Excel 2016, there is no way to change the way that Excel auto formats grouped dates in pivot tables.

The workaround is to create a new field/column in the source data file with the desired format and use that in the pivot table.