If you experience difficulty switching between full-screen and player view while using the app on a PC with an android emulator, the issue likely is from the emulator.
I’m sorry you are having difficulty using iReal pro on a platform (PC) that the app was never designed to run on.

Have you tried a different Android emulator than whatever one you are using?

Your member profile says that in addition to a Windows PC, you also have a Android tablet/phone. How does iRp work for you when using it on a device it was designed for?

)BOB