It’s designed to change for screen size. If it’s 8” or larger it will do landscape if it’s less than. 8” it will be portrait.
You can also change resolution sometimes to activate landscape on 8” tablets. Set your screen size setting bigger in android settings to try and force portrait.
It is not a setting on the app is what I’m saying. We auto scale it to portrait if it’s less than 8” if it’s bigger it auto scales to landscape
But I think you missed what I said. Within android settings and display settings you can try increasing size see if it will make resolution smaller triggering the portrait mode.