How to adjust the year on a photo in the Photos app.

In the "Image > Adjust date & Time" dialogue you have to type quickly, without hesitating between the four digits, or Photos may not read the number correctly.

Or use the up and down arrows to decrease the number of the year.

It's working here. How are you going about doing this?

kenfrompershore wrote: … know the scrolling back works, but it's a bit tedious as some of the scanned images I have are dated to the 1940's

You can select a bunch of pictures, say all the ones in the 40s, and use Adjust Date and Time to change them all at once. You will be shown the first one-- change that, and it changes all the others by the same amount. Then, you can go back and use the scroll to change 1940 to 1943, or whatever.

You can also use a script that léonie wrote. You line the pictures up in the order you want, set the date and time for the first one, and it changes all the rest to the same date, with times increasing by 1 minute each, or what increment you choose. I'm using the script for loads of old pictures.

Script: Batch Change the Date and Time to… - Apple Community

Instructions are also at that link.