I can't change the song information on my iPhone 5s. What should I do?

I have realized I put in the wrong year of an album. I went on iTunes to change it and sync it. However, when it shows up on my phone, it is still the wrong year. What has happened? How do I fix it?

Have a rummage in the iTunes sync settings. On every other similar piece of software I've used the user gets a choice regarding what happens during syncing.

If yours is set up so that what's on your iPhone takes precedence over the data held on your host computer via iTunes then the wrong information on your phone is always going to replace the information you've edited on the host computer. You need to ensure that what's on the host computer always takes precedence over what's on your iPhone; that way your edits will get transferred onto your iOS devices.