Thanks for posting!
It's possible that it's set to use the system settings instead of the file settings. These settings control the formatting for things like numbers, dates and times. Opting to use the file setting would set everything to the formatting used when the file was initially created where as using the system setting would set the formatting to whatever the system's currently using.
To change this, open the file and go to File -> File Options. Then select the Text tab and select the option to "Always use file's saved settings".