I'm trying to have my spreadsheet to sum up values by month. Note that the dates are not organised chronologically. I've tried the solutions showing here but they are not working for me. I'm not really good at this.
Here is my document: https://docs.google.com/spreadsheets/d/1rEqff3Ce_JRly4S2JJsRQP-QfQKBB9OVF9mYg-1ujl4/pubhtml