Graphics driver update

I am using an iMac (27-inch, late 2013) with 3.2Ghz Intel Fore i5, my graphics card is an Nvidia GeForce GT 755M 1GB. I have the latest version of OS. MacOS High Sierra version 10.13.3 (17D102). I subscribe to Adobe's Creative Cloud and use Photoshop, of which I also have the latest version. I have received a warning message saying that it cannot access my graphics card properly, and removes some functionality for Photoshop. How do I update my graphics driver to restore the compatibility?