● Step: 1 ●
First click the Manage symbol to the right.
● Step: 2 ●
Next, select Properties on the menu that pops up.
● Step: 3 ●
Now select Local Files, then select Browse.
● Step: 4 ●
This will take you to Drago Nokas files. Here you open the Config_EN_Steam.exe file.
● Step: 5 ●
And lastly you select either Full Screen Mode A or B
And That's It!
As I said, a pretty short guide but I've seen questions about this as it's not in the in-game menus!
Source: https://steamcommunity.com/sharedfiles/filedetails/?id=2918482639