Comment by SturgeonsLaw

Respecting regional settings is so inconsistent among Office applications. The desktop ones usually get it, but online is a crapshoot. Whenever there's a date like 3/4/25 I get the play the fun guessing game of whether that's March or April.

For Project Online, the most reliable way I found to fix it was to manually edit the URL to replace en-US with en-AU, then bookmark that.