Do you not have the gear symbol menu as per page 22 of the manual ?
The 3rd option looks to be the "Set-up section, I guess its a different firmware version to the manual if you don't have that.
I'd say raising a query with Optoma would make sense, as the manual apparently doesn't match the options your projector has. I don't supposed you need to go into the menu much, so maybe you will just need to put up with its default location, does seem odd that this feature is missing though as its been on all the Optomas I've had (I've not had a 4k one yet)