It should change the date, you choose on that page “batch edit” and click on observations made at one date
Then choose “Edit selected”
Choose the correct date at this yellow area and click “apply this”, then click “Save” at the bottom.
But if it’s hard for you to navigate batch edit, you can try editing observations individually, it will take more time, but is easier. EXIF coming from your camera doesn’t affect it now, but yes, you should change your camera settings, so new photos you make have correct date.