How to change the date stamp on individual photos taken on a Canon camera?

I own a Canon 750d at the moment, I bought it second hand not long ago. After using it for a while, I realised that the date stamps are wrong from the photos I took, two years and 4 days differences from today. I already set the correct date in the canon settings, but the photos I already took before realising, it's still taken in "2017", and appears like that when I transferred the images to my iPhone. How can I change the date individually on each and everyone? Can I do this on the camera itself? It'd make more sense rather than just connecting to a PC/Mac and change it from there.

You can't change that data.

The only way is by setting the date you want
and taking new images of the same things.

Use EXIF Date Changer. It also has a Lite version.

Connect to your computer, transfer the photos. There are plenty of third-party apps that can change the time-stamps. You can also change your system's time according to the time you need your photos to be at and then save a new copy of the photos so that the time stamp will be accurate.