Date change not accepted by Photos

I recently changed the dates of about 30 photos from the incorrect date of 2023 to the correct date of 1993. I changed each photo one by one so that the date and time matched other photos in the group. Unfortunately, when I re-opened Photos the date are back to the 2023 date. These 30 photos are from a group of about 300 that I scanned. The other 270 photos are retaining their correct date. I am running ventura 13.1 and Photos 8.0. Any suggestions??