Samsung has already started rolling out One UI Beta software update to the Galaxy S9 and S9+ smartphones in the US. Now, Samsung is now rolling out a new software update for the unlocked Galaxy S9 and S9+ units in the US.
The latest software update brings the November 2018 security patch, bug fixes, and minor improvements. The software version of this update is G960U1UES3ARJ6 and G965U1UES3ARJ6 for the Galaxy S9 and Galaxy S9 Plus respectively.
You can also check for the update manually by going into Settings > Software update > Download updates manually.