How do I disable the on-screen keyboard? (Max Lumi 13.3")

I just bought my Boox Onyx Max Lumi 13.3" for my daily writing, but the on-screen keyboard is really frustrating me.

Ideally, I would like to minimize the on-screen keyboard completely and basically pretend it doesn't exist. How do I do this?

The on-screen keyboard is incredibly distracting every time it pops up, and I don't need it since I use an external keyboard.

Things I've tried so far:

• I paired my everyday JellyComb bluetooth keyboard, but the on-screen keyboard kept popping up randomly while I typed.
• Also with my JellyComb, the Chinese keyboard kept turning on. Found out that installing the Gboard (Android app through the play store) and using it as your default seemed to help.
• I bought the special Boox keyboard because a blogger somewhere implied that would solve the issue. Now, the keyboard stays minimized while I'm typing (truly lovely), but returns the second I open a new file or edit something within the document I'm already working on.

I would so dearly appreciate any insights on how to stop the on-screen keyboard from appearing. It's such a nuisance. I've watched Boox how-to videos where the on-screen keyboard never appears, but I'm frustrated to the point of tears trying to figure out how to do it.

Thank you so much in advance.