Date format issue

[fksng66]

Hi there, I'am trying to get the last date value of each month, for example I should only be getting sum of all values on 31st May 2025, but the final value output doesn't seem to match with the expected result. I noticed that on my table the date format on the date column is mm/dd/yyyy for date 1-12, but it switched to dd/mm/yyyy starting 13-31

Is there anywhere I can change the date format to be the same? I wonder if it's why I couldn't get the correct expected result.

[fksng66]

Hi thanks for the reply, I've tried to change it on both power query and also source file but doesn't seems to make all into the same dd/mm/yyyy format still