Downgrade note 8 back to Nougat?

It's the theme that doesn't match the call UI. The theme developers need to update the themes.

Ok, thanks! That makes sense. I guess I am stuck with the call UI whether I like it or not, unless I go through the trouble of rooting and start messing around with the phone.
 
There are plenty of themes that work with Oreo including the call interface. I fell that you just haven't searched long enough to find any worthwhile. Plenty of these are free.

I wish you were right. I truly do. I am an avid theme collector. I know the theme store quite well. It is a matter of taste of course. Yes, I agree there are thousands of themes that are ok for most people. The issue is that the call UI is no longer integrated with the rest of the theme. Discerning artists in the theme store go through the trouble of theming every little element that can be themed. Most artists in the theme store and most consumers, I might add don't even notice these details, because they are happy with a generic theme , a couple of scribbles or generic colors. I am splitting hairs. This is just me. I know most consumers don't care about the details. Thanks for your comments.
 
I found out that it is not possible because the new firmware has a version 4 bootloader. The old Nougat firmware has a version 3. There is no version 4 in Nougat.
 
I wish you were right. I truly do. I am an avid theme collector. I know the theme store quite well. It is a matter of taste of course. Yes, I agree there are thousands of themes that are ok for most people. The issue is that the call UI is no longer integrated with the rest of the theme. Discerning artists in the theme store go through the trouble of theming every little element that can be themed. Most artists in the theme store and most consumers, I might add don't even notice these details, because they are happy with a generic theme , a couple of scribbles or generic colors. I am splitting hairs. This is just me. I know most consumers don't care about the details. Thanks for your comments.

I am using a theme from the samsung theme app and it does interface with the call ui. Looks the same as it did when I was on Nougat
In the US and on Oreo
 
I am using a theme from the samsung theme app and it does interface with the call ui. Looks the same as it did when I was on Nougat
In the US and on Oreo

Ah, it could be a Canadian version thing then! I went to Best Buy and tried a brand new S9+ and it had the same issue with the call UI not changing. I will check next time I am in the US. Thanks!