how do i fix this… back to full screen… thanks
I believe in the settings of a game before you launch it has these settings. It also depends on the platform you are launching it from.
You should have an option for Windowed mode full screen in the options panel. And yes, you should change this while at the character select menu.
I agree all games should have those options within the game but a lot dont these days.
For example if your launching games from Nvidia launch all the settings for the most part are selected prior to launching it including window mode/full screen options.
This game does.
You have two options:
Run windowed. Or run windowed full screen. That’s it:
https://1drv.ms/i/s!AjIesNsEIx40-htbD0G_FuKhzor5?e=xLLT97
This is not the same as full screen exclusive, which was removed, as a DX12 only game it doesn’t use that feature anymore.
Not sure you can actually with this game. Diablo IV normally will not launch at all without the battlenet app. Unlike Diablo III for example, where you could use a -launcher bypass. But it won’t work on Diablo IV. Which means most likely any other side launch won’t work, outside of Steam. But even in Steam (which I have and use for one of my alt accounts) still allows settings for the game, they aren’t gone or hidden or removed.
So.
Not sure what you are on about here with regards to this game. It may be different for some other titles though, I wouldn’t know. I use the bare minimum software with drivers, and never load things like Geforce Experience, or AMD’s similar bloatware.
But that’s me. lol
I actually didnt know this. Thank you, i should pay closer attention other than setting everything to ultra 
There was an actual full screen mode in the beta, but they removed it on day 1, because it was crashing.
Technically (as far as I can tell) Diablo IV is Blizzard’s first DX12 exclusive game. But here was an interesting article on do’s and don’ts for using DX12 while coding:
https://developer.nvidia.com/dx12-dos-and-donts
Essentially it has shifted responsibility of the game’s performance with Direct X more to the game developer rather than rely on Direct X to sort out things.
One of the main advantages was to get the developer closer to the hardware (reducing the overhead) between game engine and hardware capability. But the biggest downside is that now more work has to be done to make sure the coding takes proper advantage of it. Putting more of the responsibility on the developer.
Not to mention, the internet is littered with complaints about the overall performance of Direct X 12 not being as good as 11, and most likely due to this issue of coding the game correctly around it.
Interesting stuff.
Overwatch 2 for example is a Direct X 11 game. Not 12. Which is why it still supports full screen exclusive modes (which I don’t use).