On iPhone, iPad and Android, open iReal Pro Settings and find Auto-Hide Controls under General Settings. It was called Default to Full Screen in earlier versions.

 

Turn it on and the player controls are dismissed whenever you select another song, leaving the chart the whole screen. Leave it off (the default) and controls that were showing stay showing, which is what you want while practicing.

 

For the full guide, see Play a song on the iReal Pro website.