Hello KikiTiti,
We see you need help restoring your iPhone and updating iTunes. You may be getting that error message based on the OS version you have on the computer you installed iTunes. What that means is, your iTunes for that OS may be updated, but it is only the furthest supported iTunes version for your OS. If your OS is a bit older than the current one available, it may not support a newer version of iTunes.
- Are you using a Mac or PC?
- Which operating system version do you have installed on your computer?
We see you reached Apple Support Communities through a related article. If you are using Windows 10, make sure you've followed the guidance there: Update to the latest version of iTunes for Windows 10
There is additional guidance for restoring your iPhone using iTunes on a PC in this guide, you may need to change the iTunes version you have installed: Restore your iPhone, iPad, or iPod touch in iTunes on PC
We look forward to hearing back from you.
Take care.