Date formatting update - how to update a formula/format to properly display a date field.

Here is my example:

Raw Data in Column BM: 1/25/2017
Formula in Column BN: =MONTH(BM2)
Column BN displays a '1', in this example.

How would I update Column BN to display the month differently (Jan instead '1', Feb instead of '2', etc.)

I tried using a custom format (mmm), but I have been unable to get the formula to drag down (it keeps populating all values with 'Jan' instead of the actual expected month.

you can try with =TEXT(BM2,"mmm")