That feature is unavailable atm. but you can try using autohotkey.
From Fox Lee:
"I use a really simple AutoHotkey script to send my numpad key presses to Gazō Tuber even when I have some other window in focus. If you're interested: https://drive.google.com/file/d/1vyrpqycn1ZQgIqAvkrqA-RRAd5mCVEv5/view"